Metal Toxicity During Short‐Term Sediment Resuspension and Redeposition in a Tropical Reservoir

Billings Complex is the largest water‐storage reservoir in São Paulo, Brazil, and has been contaminated since the 1960s. Periodically, Billings sediments are subjected to currents causing resuspension and subsequent release of metals. A short‐term (4‐h) resuspension was simulated using sediment flux exposure chambers (SeFECs) to better understand the fate, bioavailability, and transport of iron (Fe), manganese (Mn), and zinc (Zn) during these events, as well as possible organism toxicity. Daphnia magna and Hyalella azteca were exposed during the 4‐h resuspension, and were monitored after exposure for survival, growth, and reproduction. Resuspension rapidly deoxygenated the overlying water, decreased the pH, and resulted in elevated dissolved Zn above the US Environmental Protection Agency’s (2002) criteria for acute toxicity (120 µg L–1). However, Zn was scavenged (after 20 h) from solution as new sorption sites formed. Dissolved Mn increased during and after resuspension, with maximum values at 20 h post exposure. An initial release of Fe occurred, likely associated with oxidation of acid‐volatile sulfides, but decreased after 1 h of resuspension. The Fe decrease is likely due to precipitation as oxyhydroxides. No acute toxicity was observed during resuspension; however, mortality of D. magna and H. azteca occurred during the postexposure period. Daphnia magna also exhibited chronic toxicity, with decreased neonate production after exposure. This sublethal effect could lead to decreased zooplankton populations over a longer period in the reservoir. Environ Toxicol Chem 2019;38:1476–1485. © 2019 SETACConceptual model of metal (Me) speciation under different sediment redox states. During bedded conditions (A) metals are mainly bounded as insoluble sulfides or associated with organic carbon (OC). When resuspended (B), sulfide species are oxidized, mobilizing metals (such as Zn) into the overlying water (OW). However, the mobilized metal is scavenged by OC and freshly‐precipitated FexOx. As particles redeposit (C), and are returned to the benthic environment, further oxidation can occur in the aerobic sediment layer releasing Fe. High dissolved Fe concentrations in OW caused acute and chronic toxicity to D. magna. Ingestion of Zn caused growth inhibition and mortality to H. azteca.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/149673/1/etc4434_am.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/149673/2/etc4434.pd

Reflection Toolkit: Strategies for Facilitating Reflection in the Classroom

This Reflection Toolkit, compiled by the faculty inquiry group (FIG), includes classroom strategies for integrating reflection into one\u27s existing syllabi. The lesson plans highlight how to encourage effective student reflections.The toolkit includes best practices to facilitate reflection in classes across the disciplines in the context of a variety of student-centered activities (including group-work, online learning, and interactive modules)

A new approach to treatment of resistant gram-positive infections: potential impact of targeted IV to oral switch on length of stay

BACKGROUND: Patients prescribed intravenous (IV) glycopeptides usually remain in hospital until completion of this treatment. Some of these patients could be discharged earlier if a switch to an oral antibiotic was made. This study was designed to identify the percentage of inpatients currently prescribed IV glycopeptides who could be discharged earlier if a switch to an oral agent was used, and to estimate the number of bed days that could be saved. We also aimed to identify the patient group(s) most likely to benefit, and to estimate the number of days of IV therapy that could be prevented in patients who remained in hospital. METHODS: Patients were included if they were prescribed an IV glycopeptide for 5 days or more. Predetermined IV to oral antibiotic switch criteria and discharge criteria were applied. A multiple logistic regression model was used to identify the characteristics of the patients most likely to be suitable for earlier discharge. RESULTS: Of 211 patients, 62 (29%) could have had a reduced length of stay if they were treated with a suitable oral antibiotic. This would have saved a total of 649 inpatient days (median 5 per patient; range 1–54). A further 31 patients (15%) could have switched to oral therapy as an inpatient thus avoiding IV line use. The patients most likely to be suitable for early discharge were those with skin and soft tissue infection, under the cardiology, cardiothoracic surgery, orthopaedics, general medical, plastic surgery and vascular specialities, with no high risk comorbidity and less than five other regularly prescribed drugs. CONCLUSION: The need for glycopeptide therapy has a significant impact on length of stay. Effective targeting of oral antimicrobials could reduce the need for IV access, allow outpatient treatment and thus reduce the length of stay in patients with infections caused by antibiotic resistant gram-positive bacteria

Laboratory and Field‐Based Assessment of the Effects of Sediment Capping Materials on Zinc Flux, Bioavailability, and Toxicity

A former mining site has been the subject of extensive remediation and restoration, with a significant focus on disconnecting mine spoils from groundwater and managing the quantity and quality of runoff. A remaining task is ensuring concentrations of zinc (Zn) in the stream outflow of a pit lake are reduced below water quality standards. The efficacy of multiple capping materials for decreasing Zn dissolution from sediments was conducted under natural and reasonable worst‐case conditions (pH = 5.5). Capping materials included AquaBlok™, limestone, and limestone–bone char. Field exposures were conducted in limnocorrals that isolated overlying water columns above the sediment and capping treatments. Simultaneous in situ and ex situ toxicity tests were conducted using Daphnia magna, Hyalella azteca, and Chironomus dilutus. In situ caged organisms were protected from temperature shock (warm epilimnetic waters) by deploying within a Toxicity Assessment Container System (TACS). Organisms were exposed to surficial sediments, caps, and hypolimnetic overlying waters for 4 d. Ex situ testing was conducted in core tube mesocosms containing sediments and caps at similar temperatures (15–19 °C). Results demonstrated the usefulness of TACS deployment in stratified lake systems. There were no differences in responses between treatments involving sediment capping materials in both in situ and ex situ tests. The lack of differences was likely due to dissolved Zn in surface water being below the hardness‐adjusted threshold effects levels (164 μg L–1). This field‐ and laboratory‐based weight‐of‐evidence study provided site‐specific data to support the selection of an effective remedy, with reduced uncertainty compared to laboratory and chemistry‐only approaches. Environ Toxicol Chem 2019;39:240–249. © 2019 SETACPeer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/152878/1/etc4612.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/152878/2/etc4612_am.pd

Ultrasound is Superior to Computed Tomography for Assessment of Medullary Nephrocalcinosis in Hypoparathyroidism

CONTEXT: Nephrocalcinosis is a complication of hypoparathyroidism and other metabolic disorders. Imaging modalities include ultrasonography (US) and computed tomography (CT). Few studies have compared these modalities, and standard clinical practice is not defined. OBJECTIVE: The objective of the study was to determine the preferred method for assessing nephrocalcinosis. DESIGN: The design of the study was a retrospective, blinded analysis. SETTING: The study was conducted at a clinical research center. PATIENTS: Twenty-two hypoparathyroid subjects and 7 controls participated in the study. INTERVENTIONS: Contemporaneous renal US and CT images were reviewed in triplicate by 4 blinded radiologists. Nephrocalcinosis was classified using a 0–3 scale with 0 meaning no nephrocalcinosis and 3 meaning severe nephrocalcinosis. MAIN OUTCOME MEASURES: Intraobserver, interobserver, and interdevice agreements were measured. RESULTS: Intraobserver agreement was high, with an overall weighted kappa of 0.83 for CT and 0.89 for US. Interobserver agreement was similar between modalities, with kappas of 0.74 for US and 0.70 for CT. Only moderate agreement was found between US and CT scores, with an intermodality kappa of 0.47 and 60% concordance. Of discordant pairs, 81% had higher US scores and only 19% had higher CT scores. Of nephrocalcinosis seen on US and not CT, 45%, 46%, and 9% were grades 1, 2, and 3, respectively. Overall, US scores were higher than CT with a cumulative odds ratio (95% confidence interval) of 5.97 (2.60, 13.75) (P < .01). In controls, 100% of US ratings were 0, and 95% of CT ratings were 0. CONCLUSIONS: US is superior to CT for assessment of mild to moderate nephrocalcinosis in patients with hypoparathyroidism. This finding, in combination with its low cost, lack of radiation, and portability, defines US as the preferred modality for assessment of nephrocalcinosis