Combined Surface-Subsurface Stream Restoration Structures Can Optimize Hyporheic Attenuation of Stream Water Contaminants.

There is a design-to-function knowledge gap regarding how engineered stream restoration structures can maximize hyporheic contaminant attenuation. Surface and subsurface structures have each been studied in isolation as techniques to restore hyporheic exchange, but surface-subsurface structures have not been investigated or optimized in an integrated manner. Here, we used a numerical model to systematically evaluate key design variables for combined surface (i.e., weir height and length) and subsurface (i.e., upstream and downstream baffle plate spacing) structures. We also compared performance metrics that place differing emphasis on hyporheic flux versus transit times. We found that surface structures tended to create higher flux, shorter transit time flowpaths, whereas subsurface structures promoted moderate-flux, longer transit time flowpaths. Optimal combined surface-subsurface structures could increase fluxes and transit times simultaneously, thus providing conditions for contaminant attenuation that were many times more effective than surface or subsurface structures alone. All performance metrics were improved by the presence of an upstream plate and the absence of a downstream plate. Increasing the weir length tended to improve all metrics, whereas the optimal weir height varied based on metrics. These findings may improve stream restoration by better aligning specific restoration goals with appropriate performance metrics and hyporheic structure designs.

Evidence of Air Dispersion: HFPO-DA and PFOA in Ohio and West Virginia Surface Water and Soil near a Fluoropolymer Production Facility.

Perfluorooctanoic acid (PFOA) was used as a fluoropolymer manufacturing aid at a fluoropolymer production facility in Parkersburg, WV from 1951 to 2013. The manufacturer introduced a replacement surfactant hexafluoropropylene oxide dimer acid (HFPO-DA) that has been in use at this site since 2013. Historical releases of PFOA and related epidemiological work in this area has been primarily focused on communities downstream. To provide an update on the ongoing impacts from this plant, 94 surface water samples and 13 soil samples were collected mainly upstream and downwind of this facility. PFOA was detected in every surface water sample with concentrations exceeding 1000 ng/L at 13 sample sites within an 8 km radius of the plant. HFPO-DA was also found to be widespread with the highest levels (>100 ng/L) found in surface water up to 6.4 km north of the plant. One sample site, 28 km north of the plant, had PFOA at 143 ng/L and HFPO-DA at 42 ng/L. Sites adjacent to landfills containing fluorochemical waste had PFOA concentrations ranging up to >1000 ng/L. These data indicate that downwind atmospheric transport of both compounds has occurred and that the boundaries of the impact zone have yet to be fully delineated.

Impact of age-related T cell dynamics on the identification of biomarkers predictive of immunotherapy discontinuation: a prospective cohort study.

BACKGROUND: The impact of biologic aging on immune checkpoint inhibitor (ICI) toxicity and efficacy is underexplored in metastatic melanoma (MM). In peripheral blood T-lymphocytes (PBTLs), biologic aging is characterized by changes in T-cell composition and cellular senescence. Whether indicators of PBTL biologic aging vary in MM patients or can be used to predict premature ICI discontinuation (pID) is unknown. METHODS: We prospectively collected PBTLs from 117 cancer-free controls and 46 MM patients scheduled to begin pembrolizumab or nivolumab monotherapy. 74 mRNAs indicative of T-cell subsets, activation, co-stimuation/inhibition and cellular senescence were measured by Nanostring. Relationships between each mRNA and chronologic age were assessed in patients and controls. Candidate biomarkers were identified by calculating the hazard ratio (HR) for pID in patients divided into low and high groups based on log-transformed mRNA levels or the magnitude by which each mRNA measurement deviated from the control trend (Δage). Area under the curve (AUC) analyses explored the ability of each biomarker to discriminate between patients with and without pID at 6 months and 1 year. RESULTS: Fifteen mRNAs correlated with chronologic age in controls, including markers of T-cell subsets, differentiation, cytokine production and co-stimulation/inhibition. None of these mRNAs remained correlated with age in patients. Median follow-up was 94.8 (1.6-195.7) weeks and 35 of 46 patients discontinued therapy (23 progression, 7 toxicity, 5 comorbidity/patient preference). Elevated pre-therapy CD8A (HR 2.2[1.1-4.9]), CD45RB (HR 2.9[1.4-5.8]) and TNFRSF14 (HR 2.2[1.1-4.5]) levels predicted pID independent of Δage-correction. CD3ε, CD27 and FOXO1 predicted pID only after Δage-correction (HR 2.5[1.3-5.1]; 3.7[1.8-7.8]; 2.1[1.1-4.3]). AUC analysis identified Δage-CD3ε and -CD27 as candidate predictors of pID (AUC=0.73; 0.75). CONCLUSIONS: Correlations between transcriptional markers of PBTL composition and chronologic age are disrupted in MM. Correcting for normal, age-related trends in biomarker expression unveils new biomarker candidates predictive of ICI outcomes.

The effect of unsteady streamflow and stream-groundwater interactions on oxygen consumption in a sandy streambed.

Streamflow dynamics are often ignored when studying biogeochemical processes in the hyporheic zone. We explored the interactive effects of unsteady streamflow and groundwater fluxes on the delivery and consumption of oxygen within the hyporheic zone using a recirculating flume packed with natural sandy sediments. The flume was equipped with a programmable streamflow control and drainage system that was used to impose losing and gaining fluxes. Tracer tests were used to measure hyporheic exchange flux and a planar optode was used to measure subsurface oxygen concentration patterns. It was found that the volume of the oxic zone decreased when the losing flux declined, and was drastically decreased when gaining conditions were applied. It was also found that unsteady streamflow led to a slight increase in the average volume of the oxic zone, compared to the average volume of the oxic zone under steady streamflow. However, the average oxygen consumption rates were significantly higher under unsteady streamflow compared to steady streamflow under all groundwater conditions with the exception of the highest losing flux. The present study provides the first insight into the interactions between streamflow unsteadiness and losing/gaining fluxes and improve understanding of their impact on microbial metabolism in the hyporheic zone.

Author Correction: Environmental filtering and community delineation in the streambed ecotone.

A correction to this article has been published and is linked from the HTML and PDF versions of this paper. The error has been fixed in the paper.

Environmental filtering and community delineation in the streambed ecotone.

A current controversy in ecology is whether biological communities are discrete biological entities or simply study units created for convenience; a debate that becomes even more heated when delimiting communities along ecotones. Here, we report an interdisciplinary study designed to address the interplay between environmental drivers and community ecology in a typical ecotone ecosystem: the streambed. Environmental filtering at a micro-scale determined how diversity, productivity and composition of the whole streambed assemblage varied with depth and with the direction of vertical water exchange. Biomass and production decreased with increasing depth, and were lower under upwelling than downwelling conditions. However, the rate at which biomass and production decreased with increasing depth differed significantly for different taxonomic groups. Using quantitative biocenosis analysis, we also showed that benthic and hyporheic zone assemblages (assemblages in close juxtaposition) could be clearly distinguished as discrete communities with individual integrity. Vertical hydrodynamic conditions also influenced the demarcation between both communities; the benthic community reached greater depths in downwelling than in upwelling zones.

Quality Improvement Intervention to Decrease Prolonged Mechanical Ventilation After Coronary Artery Bypass Surgery.

BACKGROUND: In 2010, the incidence of prolonged mechanical ventilation (> 24 hours) after isolated coronary artery bypass graft (CABG) surgery was 26.9% at the study site, The Ohio State University Wexner Medical Center, compared with the national like-hospital rate of 10.9%. OBJECTIVES: To use the principles of lean management to reduce the incidence of prolonged mechanical ventilation and to assess the sustainability of that reduction over time. METHODS: A multidisciplinary prolonged ventilation task force conducted a gap analysis leading to 3 interventions: (1) a standardized extubation protocol, (2) dry erase boards in patients' rooms to facilitate team communication, and (3) edits of the postoperative order set within the electronic health record. Outcomes of mechanical ventilation in CABG patients before and after the interventions are compared. RESULTS: All target outcomes changed significantly after the interventions, including a reduction in the median hours of initial mechanical ventilation (from 11.4 hours to 6.9 hours, P < .001). The percentage of patients reintubated did not increase (a decrease from 11.8% to 3.5% was not significant, P = .08). The rate of prolonged ventilation decreased from 29.4% to 8.6% (P = .004), and this reduction was sustained for 4 years after the interventions. CONCLUSIONS: Success factors included the multidisciplinary task force and continual protocol reeducation among front-line staff.