Publications by authors named "M G Walker"

5,865 Publications

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Low Rate of Spontaneous Closure in Premature Infants Discharged with a Patent Ductus Arteriosus: A Multicenter Prospective Study.

J Pediatr 2021 Jul 19. Epub 2021 Jul 19.

The MEDNAX Center for Research, Education, Quality and Safety, Sunrise, FL; Greenville Memorial Hospital, SC.

Objectives: To assess the rate of spontaneous closure and the incidence of adverse events in infants discharged home with a patent ductus arteriosus.

Study Design: In a prospective multicenter study, we enrolled 201 premature infants (gestational age 23-32 weeks at birth) discharged home with a persistently patent ductus arteriosus (PDA) and followed their PDA status at 6-month intervals through 18 months of age. The primary study outcome was the rate and timing of spontaneous ductal closure. Secondary outcomes included rate of assisted closure and the incidence of serious adverse events.

Results: Spontaneous ductal closure occurred in 95 infants (47%) at 12 months and 117 infants (58%) by 18 months. Seventeen infants (8.4%) received assisted closure with surgical ligation or device assisted occlusion. Three infants died (1.5%). Although infants with spontaneous closure had a higher mean birth weight and gestational age compared with infants with a persistent PDA or assisted closure, we did not identify other factors predictive of spontaneous closure.

Conclusions: Spontaneous closure of the PDA occurred in slightly less than half of premature infants discharged with a patent ductus by one year, lower than prior published reports. The high rate of assisted closure and/or adverse events in this population warrants close surveillance following discharge. Trial registration ClinicalTrials.gov: NCT02750228.
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http://dx.doi.org/10.1016/j.jpeds.2021.07.035DOI Listing
July 2021

Tau and β-amyloid burden predict actigraphy-measured and self-reported impairment and misperception of human sleep.

J Neurosci 2021 Jul 21. Epub 2021 Jul 21.

Center for Human Sleep Science, Department of Psychology, University of California Berkeley, Berkeley, CA, 94720, USA.

Alzheimer's disease (AD) is associated with poor sleep, but the impact of tau and β-amyloid (Aβ) pathology on sleep remains largely unknown. Here, we test the hypothesis that tau and Aβ predict unique impairments in objective and self-perceived human sleep under real-life, free-living conditions. Eighty-nine male and female cognitively healthy older adults received F-FTP-tau and C-PIB-Aβ PET imaging, 7 nights of sleep actigraphy and questionnaire measures, and neurocognitive assessment. Tau burden, but not Aβ, was associated with markedly worse objective sleep. In contrast, Aβ and tau were associated with worse self-reported sleep quality. Of clinical relevance, Aβ burden predicted a unique perceptual mismatch between objective and subject sleep evaluation, with individuals under-estimating their sleep. The magnitude of this mismatch was further predicted by worse executive function. Thus, early-stage tau and Aβ deposition are linked with distinct phenotypes of real-world sleep impairment, one that includes a cognitive misperception of their own sleep health.Alzheimer's disease is associated with sleep disruption, often before significant memory decline. Thus real-life patterns of sleep behavior have the potential to serve as a window into early disease progression. In 89 cognitive healthy older adults, we found that tau burden was associated with worse wristwatch actigraphy-measured sleep quality, and that both tau and β-amyloid were independently predictive of self-reported sleep quality. Furthermore, individuals with greater β-amyloid deposition were more likely to underestimate their sleep quality, and sleep quality underestimation was associated with worse executive function. These data support the role of sleep impairment as a key marker of early Alzheimer's disease, and offer the possibility that actigraphy may be an affordable and scalable tool in quantifying Alzheimer's-related behavioral changes.
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http://dx.doi.org/10.1523/JNEUROSCI.0353-21.2021DOI Listing
July 2021

Evaluating Indoor Air Chemical Diversity, Indoor-to-Outdoor Emissions, and Surface Reservoirs Using High-Resolution Mass Spectrometry.

Environ Sci Technol 2021 Jul 16. Epub 2021 Jul 16.

Department of Chemical and Environmental Engineering, Yale University, New Haven, Connecticut 06511, United States.

Detailed offline speciation of gas- and particle-phase organic compounds was conducted using gas/liquid chromatography with traditional and high-resolution mass spectrometers in a hybrid targeted/nontargeted analysis. Observations were focused on an unoccupied home and were compared to two other indoor sites. Observed gas-phase organic compounds span the volatile to semivolatile range, while functionalized organic aerosols extend from intermediate volatility to ultra-low volatility, including a mix of oxygen, nitrogen, and sulfur-containing species. Total gas-phase abundances of hydrocarbon and oxygenated gas-phase complex mixtures were elevated indoors and strongly correlated in the unoccupied home. While gas-phase concentrations of individual compounds generally decreased slightly with greater ventilation, their elevated ratios relative to controlled emissions of tracer species suggest that the dilution of gas-phase concentrations increases off-gassing from surfaces and other indoor reservoirs, with volatility-dependent responses to dynamically changing environmental factors. Indoor-outdoor emissions of gas-phase intermediate-volatility/semivolatile organic hydrocarbons from the unoccupied home averaged 6-11 mg h, doubling with ventilation. While the largest single-compound emissions observed were furfural (61-275 mg h) and acetic acid, observations spanned a wide range of individual volatile chemical products (e.g., terpenoids, glycol ethers, phthalates, other oxygenates), highlighting the abundance of long-lived reservoirs resulting from prior indoor use or materials, and their gradual transport outdoors.
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http://dx.doi.org/10.1021/acs.est.1c01337DOI Listing
July 2021

Effects of a Resident's Reputation on Laparoscopic Skills Assessment.

Obstet Gynecol 2021 Jul;138(1):16-20

Department of Obstetrics and Gynecology, University of Toronto, and the Department of Obstetrics and Gynaecology, Sinai Health System, Toronto, Ontario, the Department of Obstetrics and Gynaecology, Cumberland Regional Health Care Centre, Amherst, Nova Scotia, and the Biostatistics Research Unit, University Health Network, Toronto, Ontario, Canada.

Objective: To quantify the effect of a resident's reputation on the assessment of their laparoscopic skills.

Methods: Faculty gynecologists were randomized to receive one of three hypothetical resident scenarios: a resident with high, average, or low surgical skills. All participants were then asked to view the same video of a resident performing a laparoscopic salpingo-oophorectomy that differed only by the resident description and provide an assessment using a modified OSATS (Objective Structured Assessment of Technical Skills) and a global assessment scale.

Results: From September 6, 2020, to October 20, 2020, a total of 43 faculty gynecologic surgeons were recruited to complete the study. Assessment scores on the modified OSATS (out of 20) and global assessment (out of 5) differed significantly according to resident description, where the high-performing resident scored highest (median scores of 15 and 4, respectively), followed by the average-performing resident (13 and 3), and finally, the low-performing resident (11 and 3) (P=.008 and .043, respectively).

Conclusion: Faculty assessment of residents in gynecologic surgery is influenced by the assessor's knowledge of the resident's past performance. This knowledge introduces bias that artificially increases scores given to those residents with favorable reputations and decreases scores given to those with reputed surgical skill deficits. These data quantify the effect of such bias in the assessment of residents in the workplace and serve as an impetus to explore systems-level interventions to mitigate bias.
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http://dx.doi.org/10.1097/AOG.0000000000004426DOI Listing
July 2021