Publications by authors named "W Matthew Henderson"

1,133 Publications

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Development of bromide-selective Diffusive Gradients in Thin-Films for the measurement of average flow rate of streams.

Sci Total Environ 2021 Sep 14;788:147737. Epub 2021 May 14.

School of Science, The University of Waikato, Hamilton 3216, New Zealand; Environmental Research Institute, The University of Waikato, Hamilton 3216, New Zealand.

Diffusive Gradients in Thin-Films (DGT) have traditionally been used to measure time-weighted average concentration in water. We tested whether Br-DGT in combination with the trace-dilution flow rate method, could be used as a new approach for measuring water flow rate. A novel bromide selective DGT based on the Purolite Bromide Plus anion exchange resin (Br-DGT) was developed, which provided environmental bromide concentrations comparable to grab samples. The Br-DGT provided quantitative bromide concentrations at a range of pH, competing ion concentrations, and in synthetic natural solution. The uptake efficiency was 95.7 ± 3.4%, and the elution efficiency was 95.5 ± 4.7%. The absorption maximum/saturation point of each binding disk was 0.684 ± 0.001 mg. Bromide adsorption to the binding layer was linear to 44.1% of the total binding capacity, 0.302 mg. The determined diffusion coefficient through the agarose cross-linked polyacrylamide (APA) hydrogels was 1.05 × 10 cm s at 17.9 °C, temperature corrected to 25 °C was 1.29 × 10 cm s. DGT flow rates were between -14.7 and 6.50% of the flow independently monitored flow rate (weir). In comparison, grab sample flow rates diverged by 5.52 to 58.9% from the weir flow rate.
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http://dx.doi.org/10.1016/j.scitotenv.2021.147737DOI Listing
September 2021

Accuracy of the surgical risk preoperative assessment system universal risk calculator in predicting risk for patients undergoing selected operations in 9 specialty areas.

Surgery 2021 Apr 15. Epub 2021 Apr 15.

Surgical Outcomes and Applied Research Program, University of Colorado School of Medicine, Aurora, CO; Adult and Child Center for Health Outcomes Research and Delivery Science, University of Colorado School of Medicine, Aurora, CO; Department of Surgery, University of Colorado School of Medicine, Aurora, CO. Electronic address:

Background: The universal Surgical Risk Preoperative Assessment System prediction models for postoperative adverse outcomes have good accuracy for estimating risk in broad surgical populations and for surgical specialties. The accuracy in individual operations has not yet been assessed. The objective of this study was to evaluate the Surgical Risk Preoperative Assessment System in predicting adverse outcomes for selected individual operations.

Methods: The Surgical Risk Preoperative Assessment System models were applied to the top 2 most frequent common procedural terminology codes in 9 surgical specialties and 5 additional common general surgical operations in the 2009 to 2018 database of the American College of Surgeons National Surgical Quality Improvement Program. Goodness of fit statistics were estimated, including c-indices for discrimination, Hosmer-Lemeshow graphs and P values for calibration, overall observed versus expected event rates, and Brier scores.

Results: The total sample size was 2,020,172, which represented 29% of the 6.9 million operations in the American College of Surgeons National Surgical Quality Improvement Program database. Average c-indices across 12 outcomes were acceptable (≥0.70) for 13 (56.5%) of the 23 operations. Overall observed-to-expected rates were similar for mortality and overall morbidity across the 23 operations. Hosmer-Lemeshow graphs over quintiles of risk comparing observed-to-expected rates of mortality and overall morbidity were similar for 52% and 70% of operations, respectively. Model performance was better in less complex operations and those done in patients with lower preoperative risk.

Conclusion: Surgical Risk Preoperative Assessment System displayed accuracy in estimating postoperative adverse events for some of the 23 operations studied, but not all. In the procedures where Surgical Risk Preoperative Assessment System was not accurate, developing disease or operation-specific risk models might be appropriate.
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http://dx.doi.org/10.1016/j.surg.2021.02.033DOI Listing
April 2021

Role of Speech Pathology in a Multidisciplinary Approach to a Patient With Mild Traumatic Brain Injury.

Fed Pract 2021 Mar;38(3):136-139

is a Staff Physician, is Associate Chief of Staff, and is the Chief of Audiology/Speech Pathology Service, all at the Durham Veterans Affairs Health Care System in North Carolina. Lisa Markley is Adjunct Faculty in the Division of Speech and Hearing Sciences at the University of North Carolina School of Medicine in Chapel Hill.

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http://dx.doi.org/10.12788/fp.0097DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8040959PMC
March 2021

Hunting the eagle killer: A cyanobacterial neurotoxin causes vacuolar myelinopathy.

Science 2021 03;371(6536)

Warnell School of Forestry and Natural Resources, University of Georgia, Athens, GA, USA.

Vacuolar myelinopathy is a fatal neurological disease that was initially discovered during a mysterious mass mortality of bald eagles in Arkansas in the United States. The cause of this wildlife disease has eluded scientists for decades while its occurrence has continued to spread throughout freshwater reservoirs in the southeastern United States. Recent studies have demonstrated that vacuolar myelinopathy is induced by consumption of the epiphytic cyanobacterial species growing on aquatic vegetation, primarily the invasive Here, we describe the identification, biosynthetic gene cluster, and biological activity of aetokthonotoxin, a pentabrominated biindole alkaloid that is produced by the cyanobacterium We identify this cyanobacterial neurotoxin as the causal agent of vacuolar myelinopathy and discuss environmental factors-especially bromide availability-that promote toxin production.
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http://dx.doi.org/10.1126/science.aax9050DOI Listing
March 2021

Route of exposure influences pesticide body burden and the hepatic metabolome in post-metamorphic leopard frogs.

Sci Total Environ 2021 Jul 11;779:146358. Epub 2021 Mar 11.

U.S. Environmental Protection Agency, ORD/CEMM, Athens, GA 30605, USA.

Pesticides are being applied at a greater extent than in the past. Once pesticides enter the ecosystem, many environmental factors can influence their residence time. These interactions can result in processes such as translocation, environmental degradation, and metabolic activation facilitating exposure to target and non-target species. Most anurans start off their life cycle in aquatic environments and then transition into terrestrial habitats. Their time in the aquatic environment is generally short; however, many important developmental stages occur during this tenure. Post-metamorphosis, most species spend many years on land but migrate back to the aquatic environment for breeding. Due to the importance of both the aquatic and terrestrial environments to the life stages of amphibians, we investigated how the route of exposure (i.e., uptake from contaminated soils vs. uptake from contaminated surface water) influences pesticide bioavailability and body burden for four pesticides (bifenthrin (BIF), chlorpyrifos (CPF), glyphosate (GLY), and trifloxystrobin (TFS)) as well as the impact on the hepatic metabolome of adult leopard frogs (Gosner stage 46 with 60-90 days post-metamorphosis). Body burden concentrations for amphibians exposed in water were significantly higher (ANOVA p < 0.0001) compared to amphibians exposed to contaminated soil across all pesticides studied. Out of 80 metabolites that were putatively identified, the majority expressed a higher abundance in amphibians that were exposed in pesticide contaminated water compared to soil. Ultimately, this research will help fill regulatory data gaps, aid in the creation of more accurate amphibian dermal uptake models and inform continued ecological risk assessment efforts.
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http://dx.doi.org/10.1016/j.scitotenv.2021.146358DOI Listing
July 2021