Nitrogen source influences the interactions of comammox bacteria with aerobic nitrifiers.

While the co-existence of comammox Nitrospira with canonical nitrifiers is well documented in diverse ecosystems, there is still a dearth of knowledge about the mechanisms underpinning their interactions. Understanding these interaction mechanisms is important as they may play a critical role in governing nitrogen biotransformation in natural and engineered ecosystems. In this study, we tested the ability of two environmentally relevant factors (nitrogen source and availability) to shape interactions between strict ammonia and nitrite-oxidizing bacteria and comammox Nitrospira in continuous flow column reactors. The composition of inorganic nitrogen species in reactors fed either ammonia or urea was similar during the lowest input nitrogen concentration (1 mg-N/L), but higher concentrations (2 and 4 mg-N/L) promoted significant differences in nitrogen species composition and nitrifier abundances. The abundance and diversity of comammox Nitrospira were dependent on both nitrogen source and input concentrations as multiple comammox Nitrospira populations were preferentially enriched in the urea-fed system. In contrast, their abundance was reduced in response to higher nitrogen concentrations in the ammonia-fed system. The preferential enrichment of comammox Nitrospira in the urea-fed system could be associated with their ureolytic activity calibrated to their ammonia oxidation rates, thus minimizing ammonia accumulation, which may be partially inhibitory. However, an increased abundance of comammox Nitrospira was not associated with a reduced abundance of nitrite oxidizers in the urea-fed system while a negative correlation was found between them in the ammonia-fed system, the latter dynamic likely emerging from reduced availability of nitrite to strict nitrite oxidizers at low ammonia concentrations. IMPORTANCE: Nitrification is an essential biological process in drinking water and wastewater treatment systems for treating nitrogen pollution. The discovery of comammox Nitrospira and their detection alongside canonical nitrifiers in these engineered ecosystems have made it necessary to understand the environmental conditions that regulate their abundance and activity relative to other better-studied nitrifiers. This study aimed to evaluate two important factors that could potentially influence the behavior of nitrifying bacteria and, therefore, impact nitrification processes. Column reactors fed with either ammonia or urea were systematically monitored to capture changes in nitrogen biotransformation and the nitrifying community as a function of influent nitrogen concentration, nitrogen source, and reactor depth. Our findings show that with increased ammonia availability, comammox Nitrospira decreased in abundance while nitrite oxidizers abundance increased. Yet, in systems with increasing urea availability, comammox Nitrospira abundance and diversity increased without an associated reduction in the abundance of canonical nitrifiers.

Sunlight-Driven Photochemical Removal of Polypropylene Microplastics from Surface Waters Follows Linear Kinetics and Does Not Result in Fragmentation.

Floating microplastics are susceptible to sunlight-driven photodegradation, which can convert plastic carbon to dissolved organic carbon (DOC) and can facilitate microplastic fragmentation by mechanical forces. To understand the photochemical fate of sub-millimeter buoyant plastics, ∼0.6 mm polypropylene microplastics were photodegraded while tracking plastic mass, carbon, and particle size distributions. Plastic mass loss and carbon loss followed linear kinetics. At most time points DOC accumulation accounted for under 50% of the total plastic carbon lost. DOC accumulation followed sigmoidal kinetics, not the exponential kinetics previously reported for shorter irradiations. Thus, we suggest that estimates of plastic lifespan based on exponential DOC accumulation are inaccurate. Instead, linear plastic-C mass and plastic mass loss kinetics should be used, and these methods result in longer estimates of photochemical lifetimes for plastics in surface waters. Scanning electron microscopy revealed that photoirradiation produced two distinct patterns of cracking on the particles. However, size distribution analyses indicated that fragmentation was minimal. Instead, the initial population of microplastics shrank in size during irradiations, indicating photoirradiation in tranquil waters (i.e., without mechanical forcing) dissolved sub-millimeter plastics without fragmentation.

Sepsis mortality and ICU length of stay after the implementation of an intensive care team in the emergency department.

Emergency department patient boarding is associated with hospital mortality and increased hospital length of stay. The objective of the present study is to describe the impact of deploying an Intensive Care team in the ED and its association with sepsis mortality and ICU length of stay. Patients admitted to ICU through the ED with an ICD-10 CM diagnosis of sepsis were included. Preintervention and postintervention phases included 4 and 15 months, respectively. Sepsis time zero, SEP-1 compliance, and lag time from time zero to antibiotic administration were compared. Outcomes of interest were mortality and ICU LOS. 1021 septic patients were included. Sixty-six percent fulfilled compliance with 3 h SEP-1 bundle. Lag time from time zero to antibiotic administration was 75 min. Multivariate analysis showed no association between ICU team in the ED and hospital mortality (Log OR 0.94, CI 0.67-1.34; p = 0.73). The ICU team in the ED was associated with prolonged ICU LOS (Log OR 1.21, CI 1.13-1.30; p < 0.01). Septic shock and ED boarding time were associated with prolonged ICU LOS. Compliance with SEP-1 bundle was associated with its reduction. Implementation of an ICU team in the ED for the treatment of septic patients during high volume hospitalizations is not associated with a reduction of mortality or ICU LOS.

An optimized acidic digestion for the isolation of microplastics from biota-rich samples and cellulose acetate matrices.

Plastic pollution is a growing concern. To analyze plastics in environmental samples, plastics need to be isolated. We present an acidic/oxidative method optimized to preserve plastics while digesting synthetic cellulose acetate and a range of organics encountered in environmental samples. Cellulose acetate was chosen for optimization as it can be purchased as a reference material, can co-occur with plastics in environmental samples and, if it can be completely digested, is a potential filter material for the collection of nano- and micro-plastics from natural waters. Other forms of particulate organic matter (POM) were chosen to provide a range of chemistries that might alter digestion efficiency and due to the interest in the community of isolating plastics from samples where these organics occur. For instance, microalgal POM occurs in lake and ocean waters, riverine POM in rivers, and inclusion of tuna provides a test for the suitability of the method for isolating plastics from animal tissues. The method is a one-pot overnight (16-18 h) digestion in 5 M nitric acid with 0.3 M sodium persulfate heated to 80 °C. The method provides quantitative removal of cellulose acetate (exceeding detection limits), near quantitative removal of microalgal POM and Albacore tuna tissue (>99%), but only 86% of urban river POM, all while retaining >99% by mass of C-C bonded polymers polyethylene, polypropylene, and polystyrene and >96% by mass of polyethylene terephthalate. Fourier transform infrared spectroscopy (FT-IR) and %-C content analysis confirmed plastic polymer stability during digestion. However, some additives in appear susceptible to digestion with FT-IR results indicating the loss of N,N'-ethylenebis(stearamide) from polyethylene. This method provides a simpler and more effective method than many in the literature. We present recommendations for the application of this method, as well as limitations and areas for future improvement.

Acute interstitial pneumonia due to amyopathic dermatomyositis.

Clinically amyopathic dermatomyositis usually presents with severe skin rashes but no muscle involvement and is associated with the highly lethal form of rapidly progressive interstitial lung disease. Diagnosis of myositis-related acute interstitial pneumonia can be particularly challenging, as the clinical presentation of hypoxia and respiratory failure has a broad differential diagnosis. This is especially true when the characteristic skin or muscle finding are absent and the patient has no history of idiopathic inflammatory myopathies. We present a rare case of a patient who presented with rapidly worsening acute respiratory failure from acute interstitial pneumonia due to an undiagnosed amyopathic dermatomyositis with positive anti-MDA5 autoantibody without any of the typical myositis symptoms or physical exam findings.

Implementation of a medical intensive care team in the emergency department of a tertiary medical center in the USA.

OBJECTIVE: Critically ill patients boarding in the ED have higher mortality rates. Several strategies have been implemented to deliver care to boarding patients. Our institution opted for a strategy consisting on deploying an Intensive Care team in the ED. This article reports outcomes before-and-after implementation of that team. METHODS: On November 2020, a Medical Intensive Care Team was deployed in the ED. The team performed consultations for ICU patients boarding in the ED. A retrospective analysis of critically ill patients arriving to the ED before-and-after team implementation was performed. Outcome data were reviewed. Direct hospitalization costs per patient, and direct costs per department were assessed. Wilcoxon rank sum and Chisq-test were utilized to compare differences pre- and post-implementation. Multivariate analyses to model outcomes toward pre- and post-implementation and other variables were performed. RESULTS: 1,828 and 3,272 patients were included in the pre- and post-intervention groups. ICU LOS (days) pre- and post-intervention were 3 (1,6) and 3 (1,6), respectively (p = 0.41). ICU readmission rates were 6.7% pre-intervention and 7.4% post-intervention (p = 0.37). Total direct costs were US$ 19,928 (11,006, 37,815) and US$ 15,795 (9016, 28,993), respectively (p < 0.01). Multivariate analysis showed no association between team deployment and ICU LOS or readmission. However, there was association between its implementation and hospitalization cost reduction per patient of US$ 7,171. CONCLUSION: The implementation of a Medical Intensive Care team in the ED is not associated with a reduction of ICU LOS or ICU readmission. Nevertheless, its implementation is associated with a reduction of hospitalization costs.

Critically ill patients boarding in the emergency department and the association with intensive care unit length of stay and hospital mortality during the COVID-19 pandemic.

Boarding of critically ill patients in the emergency department (ED) has been associated with mortality and intensive care unit (ICU) length of stay (LOS). This study evaluated whether boarding time in the ED was associated with those outcomes. A retrospective analysis of patients admitted through the ED to the ICU was performed. Information on demographics, severity score, and diagnoses was collected. The continuous primary endpoint of ICU LOS was fitted by a log normal model on covariates, including ED LOS. A multivariate log normal model was also used to model covariates toward ICU LOS. The binary patient expiration status was modeled by univariate and multivariate logistic regressions to evaluate the association of mortality with covariates. ED LOS was not associated with ICU LOS (correlation with an estimate of -0.02 ± 0.06 [SE], P = 0.76). ED LOS was not associated with hospital mortality (estimate correlation of -0.07 ± 0.07 [SE], P = 0.33). Body mass index, APACHE IV score, mechanical ventilation, and diagnosis of COVID-19 were associated with LOS. Age, APACHE IV score, mechanical ventilation, sepsis, and COVID-19 were associated with mortality. In conclusion, ED LOS is not associated with ICU LOS or hospital mortality. These findings may be related to early therapeutic interventions applied in the ED.

A DNA-Based MRI Contrast Agent for Quantitative pH Measurement.

Extracellular pH is important in clinical measurements due to its correlation to cell metabolism and disease progression. In MRI, T1/T2 ratiometric analysis and other methods have been previously applied to quantify pH using conventional pulse sequences. However, for nanoparticle-based approaches, heterogeneity in size and surface functionalization tends toward qualitative rather than quantitative results. To address this limitation, we developed a novel DNA-based MRI contrast agent, pH-DMRCA, which utilizes a highly programmable and reproducible nanostructure. The pH-DMRCA is a dendritic DNA scaffold that is functionalized with a pH-responsive MRI-sensitive construct, Gd(NP-DO3A), at the end of each DNA arm. We first evaluated the r1 and r2 response of our pH-DMRCA over a range of pH values (pH = 5-9) to establish a relaxometric model of pH. These MRI-based assessments of pH were validated in a separate set of samples using a pH electrode (n = 18) and resulted in a good linear correlation (R2 = 0.99, slope = 0.98, intercept = 0). A Bland-Altman analysis of the results also showed reasonable agreement between the calculated pH and measured pH. Moreover, these pH comparisons were consistent across three different pH-DMRCA concentrations, demonstrating concentration-independence of the method. This MRI-based pH quantification methodology was further verified in human blood plasma. Given the versatility of the DNA-based nanostructures, the contrast agent has a potential to be applied to a wide variety of imaging applications where extracellular pH is important including cancer, stroke, cardiovascular disease, and other important diseases.

Recent Developments in Nanosensors for Imaging Applications in Biological Systems.

Sensors are key tools for monitoring the dynamic changes of biomolecules and biofunctions that encode valuable information that helps us understand underlying biological processes of fundamental importance. Because of their distinctive size-dependent physicochemical properties, materials with nanometer scales have recently emerged as promising candidates for biological sensing applications by offering unique insights into real-time changes of key physiological parameters. This review focuses on recent advances in imaging-based nanosensor developments and applications categorized by their signal transduction mechanisms, namely, fluorescence, plasmonics, MRI, and photoacoustics. We further discuss the synergy created by multimodal nanosensors in which sensor components work based on two or more signal transduction mechanisms.

Visual memory in patients after anterior right temporal lobectomy and adult normative data for the Brown Location Test.

Several large meta-analytic studies have failed to support a consistent relationship between visual or "nonverbal" memory deficits and right mesial temporal lobe changes. The Brown Location Test (BLT), a recently developed dot location learning and memory test, uses a nonsymmetrical array and provides control over many of the confounding variables (e.g., verbal influence and drawing requirements) inherent in other measures of visual memory. In the present investigation, we evaluated the clinical utility of the BLT in patients who had undergone left or right anterior mesial temporal lobectomy. We also provide normative data of 298 healthy adults for standardized scores. Results revealed significantly worse performance on the BLT in the right as compared to the left lobectomy group and the healthy adult normative sample. The present findings support a role for the right anterior mesial temporal lobe in dot location learning and memory.