Scholarship & History
The UMB Digital Archive is a service of the Health Sciences and Human Services Library (HS/HSL) that collects, preserves, and distributes the academic works of the University of Maryland, Baltimore. It is a place that digitally captures the historical record of the campus.
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Comprehensive evaluations of diurnal NO measurements during DISCOVER-AQ 2011: effects of resolution-dependent representation of NO emissions.Nitrogen oxides (NO x =NO+NO2) play a crucial role in the formation of ozone and secondary inorganic and organic aerosols, thus affecting human health, global radiation budget, and climate. The diurnal and spatial variations in NO2 are functions of emissions, advection, deposition, vertical mixing, and chemistry. Their observations, therefore, provide useful constraints in our understanding of these factors. We employ a Regional chEmical and trAnsport model (REAM) to analyze the observed temporal (diurnal cycles) and spatial distributions of NO2 concentrations and tropospheric vertical column densities (TVCDs) using aircraft in situ measurements and surface EPA Air Quality System (AQS) observations as well as the measurements of TVCDs by satellite instruments (OMI: the Ozone Monitoring Instrument; GOME-2A: Global Ozone Monitoring Experiment - 2A), ground-based Pandora, and the Airborne Compact Atmospheric Mapper (ACAM) instrument in July 2011 during the DISCOVER-AQ campaign over the Baltimore-Washington region. The model simulations at 36 and 4 km resolutions are in reasonably good agreement with the regional mean temporospatial NO2 observations in the daytime. However, we find significant overestimations (underestimations) of model-simulated NO2 (O3) surface concentrations during night-time, which can be mitigated by enhancing nocturnal vertical mixing in the model. Another discrepancy is that Pandora-measured NO2 TVCDs show much less variation in the late afternoon than simulated in the model. The higher-resolution 4 km simulations tend to show larger biases compared to the observations due largely to the larger spatial variations in NO x emissions in the model when the model spatial resolution is increased from 36 to 4 km. OMI, GOME-2A, and the high-resolution aircraft ACAM observations show a more dispersed distribution of NO2 vertical column densities (VCDs) and lower VCDs in urban regions than corresponding 36 and 4 km model simulations, likely reflecting the spatial distribution bias of NO x emissions in the National Emissions Inventory (NEI) 2011.
Impact of Palliative Care on Interhospital Transfers to the Intensive Care Unit.Community hospitals will often transfer their most complex, critically ill patients to intensive care units (ICUs) of tertiary care centers for specialized, comprehensive care. This population of patients has high rates of morbidity and mortality. Palliative care involvement in critically ill patients has been demonstrated to reduce over-utilization of resources and hospital length of stays. We hypothesized that transfers from community hospitals had low rates of palliative care involvement and high utilization of ICU resources. In this single-center retrospective cohort study, 848 patients transferred from local community hospitals to the medical ICU (MICU) and cardiac care unit (CCU) at a tertiary care center between 2016-2018 were analyzed for patient disposition, length of stay, hospitalization cost, and time to palliative care consultation. Of the 848 patients, 484 (57.1%) expired, with 117 (13.8%) having expired within 48 hours of transfer. Palliative care consult was placed for 201 (23.7%) patients. Patients with palliative care consult were statistically more likely to be referred to hospice (p<0.001). Over two-thirds of palliative care consults were placed later than 5 days after transfer. Time to palliative care consult was positively correlated with length of hospitalization among MICU patients (r=0.79) and CCU patients (r=0.90). Time to palliative consult was also positively correlated with hospitalization cost among MICU patients (r=0.75) and CCU patients (r=0.86). These results indicate early palliative care consultation in this population may result in timely goals of care discussions and optimization of resources.
Drug costs in context: assessing drug costs in cost-of-illness analyses.Cost-of-illness (COI) studies attempt to measure and describe the costs associated or attributed to a specific disease, but there are several considerations for measuring and interpreting drug costs estimates. The complexity of the pharmaceutical supply chain and contractual relationships between manufacturers, wholesalers, pharmacies and payers create challenges for researchers attempting to include drug costs in COI analyses. This article aims to provide contextual information for a general audience interested in conducting or evaluating COI studies that may include drug costs and to describe key factors to consider when reviewing drug costs in the peer-reviewed literature.
Exploring the impacts of learning modality changes: Validation of the learning modality change community of inquiry and self-efficacy scalesThe rapid learning environment transition initiated by the COVID-19 pandemic impacted students’ perception of, comfort with, and self-efficacy in the online learning environment. Garrison’s Community of Inquiry framework provides a lens for examining students’ online learning experiences through three interdependent elements: social presence, cognitive presence, and teaching presence. Researchers in this study developed and validated the Learning Modality Change Community of Inquiry and Self-Efficacy scales to measure health professions students’ self-efficacy with online learning, while exploring how cognitive, social, and teaching presence is experienced by students who transition from one learning environment to another. The two scales demonstrate strong validity and reliability evidence and can be used by educators to explore the impacts of learning modality changes on student learning experiences. As learning environments continue to evolve, understanding the impact of these transitions can inform how educators consider curriculum design and learning environment changes. © 2022, The Author(s).
Differential effects of metformin-mediated BSEP repression on pravastatin and bile acid pharmacokinetics in humans: A randomized controlled trial.Metformin has been shown to repress transcription of the bile salt export pump (BSEP) in human primary hepatocytes. The primary objective of this study was to assess the effect of oral metformin on the human pharmacokinetics (PKs) of two BSEP probe substrates: pravastatin and chenodeoxycholic acid (CDCA; also known as chenodiol). Endogenous bile acid levels were assessed as a secondary measure of metformin impact. An open-label, randomized, single-dose, placebo-controlled, fasted, crossover PK study was conducted in 12 healthy adult volunteers. Metformin (500 mg b.i.d.) or placebo (b.i.d.) was administered orally for 6 days. On day 7, a single dose of the BSEP substrates pravastatin (80 mg) and CDCA (250 mg) were administered orally. Plasma samples were quantified for pravastatin, CDCA, and endogenous bile acids. Compared to placebo, metformin increased pravastatin plasma exposure, did not impact CDCA plasma exposure, and reduced conjugated primary bile acid levels in the blood. These results are consistent with metformin repressing BSEP expression. This differential effect reflects the degree of enterohepatic recirculation of victim substrates. © 2022 The Authors.