Fecal Impairment Framework, A New Conceptual Framework for Assessing Fecal Contamination in Recreational Waters.

Fecal pollution of surface water is a pervasive problem that negatively affects waterbodies concerning both public health and ecological functions. Current assessment methods monitor fecal indicator bacteria (FIB) to identify pollution sources using culture-based quantification and microbial source tracking (MST). These types of information assist stakeholders in identifying likely sources of fecal pollution, prioritizing them for remediation, and choosing appropriate best management practices. While both culture-based quantification and MST are useful, they yield different kinds of information, potentially increasing uncertainty in prioritizing sources for management. This study presents a conceptual framework that takes separate human health risk estimates based on measured MST and E. coli concentrations as inputs and produces an estimate of the overall fecal impairment risk as its output. The proposed framework is intended to serve as a supplemental screening tool for existing monitoring programs to aid in identifying and prioritizing sites for remediation. In this study, we evaluated the framework by applying it to two primarily agricultural watersheds and several freshwater recreational beaches using existing routine monitoring data. Based on a combination of E. coli and MST results, the proposed fecal impairment framework identified four sites in the watersheds as candidates for remediation and identified temporal trends in the beach application. As these case studies demonstrate, the proposed fecal impairment framework is an easy-to-use and cost-effective supplemental screening tool that provides actionable information to managers using existing routine monitoring data, without requiring specialized expertize.

Frequency and degradation of SARS-CoV-2 markers N1, N2, and E in sewage.

Coronavirus disease 2019 (COVID-19) is an infectious disease that is mainly spread through aerosolized droplets containing severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and is excreted in feces by infected individuals. Sewage surveillance has been applied widely to obtain data on the prevalence of COVID-19 in whole communities. We used SARS-CoV-2 gene targets N1, N2, and E to determine the prevalence of COVID-19 at both municipal and building levels. Frequency analysis of wastewater testing indicated that single markers detected only 85% or less of samples that were detected as positive for SARS-CoV-2 with the three markers combined, indicating the necessity of pairing markers to lower the false-negative rate. The best pair of markers in both municipal and building level monitoring was N1 and N2, which correctly identified 98% of positive samples detected with the three markers combined. The degradation rates of all three targets were assessed at two different temperatures (25 and 35 °C) as a possible explanation for observed differences between markers in frequency. Results indicated that all three RNA targets degrade at nearly the same rate, indicating that differences in degradation rate are not responsible for the observed differences in marker frequency.

Using watershed characteristics to enhance fecal source identification.

Fecal pollution is one of the most prevalent forms of pollution affecting waterbodies worldwide, threatening public health and negatively impacting aquatic environments. Microbial source tracking (MST) applies polymerase chain reaction (PCR) technology to help identify the source of fecal pollution. In this study, we combine spatial data for two watersheds with general and host-associated MST markers to target human (HF183/BacR287), bovine (CowM2), and general ruminant (Rum2Bac) sources. Concentrations of MST markers in samples were determined with droplet digital PCR (ddPCR). The three MST markers were detected at all sites (n = 25), but bovine and general ruminant markers were significantly associated with watershed characteristics. MST results, combined with watershed characteristics, suggest that streams draining areas with low-infiltration soil groups and high agricultural land use are at an increased risk for fecal contamination. Microbial source tracking has been applied in numerous studies to aid in identifying the sources of fecal contamination, but these studies usually lack information on the involvement of watershed characteristics. Our study combined watershed characteristics with MST results to provide more comprehensive insight into the factors that influence fecal contamination in order to implement the most effective best management practices.

Quality and Perceived Usefulness of Patient-Submitted Store-and-Forward Teledermatology Images.

Importance: Patient-submitted images vary considerably in quality and usefulness. Studies that characterize patient-submitted images in a real-life setting are lacking. Objective: To evaluate the quality and perceived usefulness of patient-submitted images as determined by dermatologists and characterize agreement of their responses. Design, Setting, and Participants: This survey study included patient images submitted to the Department of Dermatology at Duke University (Durham, North Carolina) between August 1, 2018, and December 31, 2019. From a total pool of 1200 images, 10 dermatologists evaluated 200 or 400 images each, with every image being evaluated by 3 dermatologists. Data analysis occurred during the year leading up to the article being written. Main Outcomes and Measures: The primary outcomes were the responses to 2 questions and were analyzed using frequency counts and interrater agreement (Fleiss κ) to assess image quality and perceived usefulness. We performed a random-effects logistic regression model to investigate factors associated with evaluators' decision-making comfort. We hypothesized that most images would be of low quality and perceived usefulness, and that interrater agreement would be poor. Results: A total of 259 of 2915 patient-submitted images (8.9%) did not depict a skin condition at all. The final analysis comprised 3600 unique image evaluations. Dermatologist evaluators indicated that 1985 images (55.1%) were useful for medical decision-making and 2239 (62.2%) were of sufficient quality. Interrater agreement for a given image's diagnostic categorization was fair to substantial (κ range, 0.36-0.64), while agreement on image quality (κ range, 0.35-0.47) and perceived usefulness (κ range, 0.29-0.38) were fair to moderate. Senior faculty had higher odds of feeling comfortable with medical decision-making than junior faculty (odds ratio [OR], 3.68; 95% CI, 2.9-4.66; P < .001) and residents (OR, 5.55; 95% CI, 4.38-7.04; P < .001). Images depicting wounds (OR, 1.75; 95% CI, 1.18-2.58; P = .01) compared with inflammatory skin conditions and that were in focus (OR, 5.56; 95% CI, 4.63-6.67; P < .001) had higher odds of being considered useful for decision-making. Conclusions and Relevance: In this survey study including 10 dermatologists, a slight majority of patient-submitted images were judged to be of adequate quality and perceived usefulness. Fair agreement between dermatologists was found regarding image quality and perceived usefulness, suggesting that store-and-forward teledermatology initiatives should consider a physician's individual experiences and comfort level. The study results suggest that images are most likely to be useful when they are in focus and reviewed by experienced attending physicians for wound surveillance, but dermatologists may be burdened by irrelevant or unsuitable images.

Effects of coagulant morphology and chemical properties on soluble reactive phosphate removal in corn ethanol wastewater.

As ethanol production continues to rise around the world, and wastewater discharge requirements for phosphorus become more stringent, it is important that phosphorus removal technologies are evaluated on ethanol wastewater streams. In this study, five coagulating agents with distinct characteristics were evaluated for their soluble reactive phosphate (SRP) removal performance on both a synthetic wastewater sample and a wastewater sample collected from a corn ethanol manufacturer. All coagulants demonstrated a positive correlation between coagulant dose and percent removal of SRP on both samples. Alum and ferric chloride produced the highest SRP removal efficiencies on both the ethanol and synthetic wastewater, indicating that prepolymerized, high-basicity coagulants (e.g., aluminum chlorohydrate, poly-aluminum ferric chloride) are less effective for SRP removal than nonpolymerized coagulants. The background matrix analysis combined with the pH studies revealed that the high alkalinity in the ethanol wastewater has a substantial inhibitory effect on SRP removal capacity that supersedes pH effects. These experimental results suggest that the Al-Al and Al-OH bonds in the heavily hydroxylated and polymerized structure of high-basicity coagulants are very rigid, which could prevent inner-sphere complexation and drive a less effective outer-sphere interaction, thus hindering SRP removal efficiency. PRACTITIONER POINTS: Five different coagulants are evaluated for reactive phosphate removal from wastewater. Alum and ferric chloride show higher removal efficiency than prepolymerized and high-basicity coagulants. Optimal removal pH increases with increasing coagulant basicity.

Mercury methylation potential in a sand dune on Lake Michigan's eastern shoreline.

Lake Michigan hosts the largest freshwater sand dune system in the world and is economically important for the fishery industry and tourism. Due to industrial pollution and atmospheric mercury (Hg) deposition, toxic levels of methylmercury (MeHg) have been found in the Lake biota, but little information is known regarding MeHg sources and Hg methylation potential in the shoreline sand dunes. We conducted anaerobic incubation experiments with beach sands collected from Ludington, Michigan, and examined the effects of organic carbon substrate addition, inorganic nitrogen, and mineral magnetite on Hg methylation. Despite nutrient poor and low-organic carbon conditions, appreciable Hg methylation activity coupled with carbon degradation was observed in the sands. Addition of acetate as a carbon source substantially increased MeHg production from 2 to 380 ng/kg sediment while acetate was rapidly degraded in the first 19 days of incubation. Ammonium addition showed little influence on carbon degradation or Hg methylation, whereas iron oxide addition (~1% dry weight) significantly inhibited both carbon degradation and MeHg production (by up to 90%), highlighting strongly coupled interactions between microbes, carbon substrates, and minerals. This research demonstrates the potential of microbial Hg methylation in the sand dunes, which may play a role in MeHg input and bioaccumulation in the Lake Michigan ecosystem.

Effect of copper salts on hydrothermal oxidative decarboxylation: a study of phenylacetic acid.

Decarboxylation of carboxylic acids is favored under hydrothermal conditions, and can be influenced by dissolved metals. Here, we use phenylacetic acid as a model compound to study its hydrothermal decarboxylation in the presence of copper(ii) salts but no O2. Our results showed a strong oxidizing role of copper in facilitating oxidative decarboxylation.

Temperature sensitivity of mineral-enzyme interactions on the hydrolysis of cellobiose and indican by ß-glucosidase.

Extracellular enzymes are mainly responsible for depolymerizing soil organic matter (SOM) in terrestrial ecosystems, and soil minerals are known to affect enzyme activity. However, the mechanisms and the effects of mineral-enzyme interactions on enzymatic degradation of organic matter remain poorly understood. In this study, we examined the adsorption of fungal ß-glucosidase enzyme on minerals and time-dependent changes of enzymatic reactivity, measured by the degradation of two organic substrates (i.e., cellobiose and indican) under both cold (4 °C) and warm (20 and 30 °C) conditions. Hematite, kaolinite, and montmorillonite were used, to represent three common soil minerals with distinctly different surface charges and characteristics. ß-glucosidase was found to sorb more strongly onto hematite and kaolinite than montmorillonite. All three minerals inhibited enzyme degradation of cellobiose and indican, likely due to the inactivation or hindrance of enzyme active sites. The mineral-bound ß-glucosidase retained its specificity for organic substrate degradation, and increasing temperature from 4 to 30 °C enhanced the degradation rates by 2-4 fold for indican and 5-9 fold for cellobiose. These results indicate that enzyme adsorption, mineral type, temperature, and organic substrate specificity are important factors influencing enzymatic reactivity and thus have important implications in further understanding and modeling complex enzyme-facilitated SOM transformations in terrestrial ecosystems.

Erythema ab igne in patients with sickle cell disease.

Erythema ab igne (EAI) is an asymptomatic dermatosis caused by prolonged exposure to localized heat. Affected areas have net-like hyperpigmentation that may resemble more serious conditions such as livedo racemosa or vasculitis. We report three cases of EAI in pediatric sickle cell disease (SCD) patients who were initially suspected of having a more severe, life-threatening disorder before Dermatology was consulted. Clinicians caring for pediatric SCD patients who regularly use heating pads/devices for pain relief should consider EAI in the differential diagnosis of large areas of net-like hyperpigmentation. This paper aims to increase recognition of EAI and patient education on safe practices while using heating pads.

A 17-Year-Old With Chest Pain.

A 17-year-old male subject with a history of deep venous thrombosis presented with acute unilateral severe chest pain. His examination was nonspecific, and vital signs were normal. His initial laboratory evaluation revealed mild thrombocytopenia, elevated troponin levels, and critically elevated activated partial thromboplastin time. A computed tomography angiogram of the chest revealed a pulmonary embolus, and anticoagulation therapy was initiated. His course was complicated by the development of multiple thrombi and respiratory failure. Extensive evaluation revealed a rare, underlying diagnosis in time for life-saving treatment to be initiated.