Publications by authors named "David C Simpson"

Objective: To explore parental perspectives on the use of technology in neonatal intensive care units (NICU), and its impact during COVID-19 parental presence restrictions.

Methods: Co-designed online survey targeting parents of infants admitted to a Canadian NICU from March 1st, 2020 until March 5th, 2021.

Results: Parents (n = 117) completed the survey from 38 NICUs.

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Objectives: To conduct a needs assessment with families and their healthcare team to understand the impact of restrictive family presence policies in the neonatal intensive care unit (NICU) in response to COVID-19.

Background: In response to the COVID-19 pandemic, significant restrictive family presence policies were instituted in most NICUs globally intended to protect infants, families, and HCPs. However, knowledge on the impact of the stress of the pandemic and policies restricting family presence in the NICU on vulnerable neonates and their families remains limited.

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Objectives of this study were to determine whether single-family room (SFR) design enhances parental presence, involvement, and maternal well-being during neonatal intensive care hospitalization. An observational cohort including mothers of infants was randomly assigned to receive care in a tertiary-level open-bay (OB) (n = 35) or SFR (n = 36). Mothers were asked to complete daily diaries documenting parental presence, involvement in care, and questionnaires examining maternal well-being.

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Article Synopsis
  • In response to COVID-19, neonatal intensive care units (NICUs) restricted family presence, leading to communication issues and challenges in family integrated care.
  • The study aimed to create clinical care pathways to support families during these parental presence restrictions.
  • Three virtual care pathways were developed: fostering relationships between families and healthcare providers, improving awareness of available resources, and providing consistent COVID-19 messaging, resulting in more equitable family-centered care.
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Background: Presence in the neonatal intensive care unit (NICU) is a vital step for caregivers initiating involvement, such as skin-to-skin contact, holding or singing/reading to their newborn. Little is known about caregiver presence and involvement in Canadian NICU's context by caregiver type (mother, father, other), and the association between maternal presence and key maternal and newborn characteristics.

Purpose: The primary objective was to examine the presence and involvement of family caregivers in the NICU.

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Background: Cytochrome c (Cyt c) is a mobile component of the electron transport chain (ETC.) which contains a tightly coordinated heme iron. In pathologic settings, a key ligand of the cyt c's heme iron, methionine (Met80), is oxidized allowing cyt c to participate in reactions as a peroxidase with cardiolipin as a target.

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Exposure to Paraquat and RNA interference knockdown of mitochondrial superoxide dismutase (Sod2) are known to result in significant lifespan reduction, locomotor dysfunction, and mitochondrial degeneration in Drosophila melanogaster. Both perturbations increase the flux of the progenitor ROS, superoxide, but the molecular underpinnings of the resulting phenotypes are poorly understood. Improved understanding of such processes could lead to advances in the treatment of numerous age-related disorders.

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Mass spectrometry was used to investigate the effects of exposing mitochondrial aconitase (ACO2) to the membrane lipid peroxidation product, 4-hydroxy-2-(E)-nonenal (HNE). ACO2 was selected for this study because (1) it is known to be inactivated by HNE, (2) elevated concentrations of HNE-adducted ACO2 have been associated with disease states, (3) extensive structural information is available, and (4) the iron-sulfur cluster in ACO2 offers a critical target for HNE adduction. The aim of this study was to relate the inactivation of ACO2 by HNE to structural features.

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Mass spectrometry was used to probe the preferred locations of trans-4-hydroxy-2-nonenal (HNE) addition to the cysteine, histidine, and lysine residues of human serum albumin (HSA). Considering only those modified peptides supported by high mass accuracy Orbitrap precursor ion measurements (high confidence hits), with HNE:HSA ratios of 1:1 and 10:1, 3 and 15 addition sites, respectively, were identified. Using less stringent criteria, a total of 34 modifications were identified at the higher concentration.

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The potent lipid mediator sphingosine-1-phosphate (S1P) regulates diverse physiological processes by binding to 5 specific GPCRs, although it also has intracellular targets. Here, we demonstrate that S1P, produced in the mitochondria mainly by sphingosine kinase 2 (SphK2), binds with high affinity and specificity to prohibitin 2 (PHB2), a highly conserved protein that regulates mitochondrial assembly and function. In contrast, S1P did not bind to the closely related protein PHB1, which forms large, multimeric complexes with PHB2.

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Background: Plasmodium falciparum placental malaria (PM) contributes to 10,000 maternal deaths due to severe anemia (SA) each year in Africa, primarily among primigravid women who are most susceptible. Increased levels of proinflammatory cytokines like TNF-alpha are associated with maternal anemia in first time mothers but not in other women. Here we aimed to identify additional changes in the plasma proteome associated with pregnancy malaria that may contribute to the development of malaria-related maternal anemia.

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The proton affinities of the 20 common amino acids have been computed at the G3MP2 level using structures derived from broad conformational searches at a variety of levels including G3MP2. In some cases, the conformational surveys identified more stable species than had been used in previous studies of proton affinities, though the differences in energy are sometimes rather small. The present values are likely the most reliable measure of amino acid proton affinities in the gas phase.

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We investigated the combination of weak anion exchange (WAX) fractionation and on-line reversed-phase liquid chromatography (RPLC) separation using a 12 T FTICR mass spectrometer for the detection of intact proteins from a Shewanella oneidensis MR-1 cell lysate. This work aimed at optimizing intact protein detection for profiling proteins at a level that incorporates their modification state. A total of 715 intact proteins were detected, and the combined results from the WAX fractions and the unfractionated cell lysate were aligned using LC-MS features to facilitate protein abundance measurements.

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Bottom-up proteomics (analyzing peptides that result from protein digestion) has demonstrated capability for broad proteome coverage and good throughput. However, due to incomplete sequence coverage, this approach is not ideally suited to the study of modified proteins. The modification complement of a protein can best be elucidated by analyzing the intact protein.

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Mass spectrometry (MS)-based proteomics is currently dominated by the analysis of peptides originating either from digestion of proteins separated by two-dimensional gel electrophoresis (2-DE) or from global digestion; the simple peptide mixtures obtained from digestion of gel-separated proteins do not usually require further separation, while the complex peptide mixtures obtained by global digestion are most frequently separated by chromatographic techniques. Capillary electrophoresis (CE) provides alternatives to 2-DE for protein separation and alternatives to chromatography for peptide separation. This review attempts to elucidate how the most promising CE modes, capillary zone electrophoresis (CZE) and capillary isoelectric focusing (CIEF), might best be applied to MS-based proteomics.

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