Mechanisms and Opportunities for Rational In Silico Design of Enzymes to Degrade Per- and Polyfluoroalkyl Substances (PFAS)

Per and polyfluoroalkyl substances (PFAS) present a unique challenge to remediation techniques because their strong carbon−fluorine bonds make them difficult to degrade. This review explores the use of in silico enzymatic design as a potential PFAS degradation technique. The scope of the enzymes included is based on currently known PFAS degradation techniques, including chemical redox systems that have been studied for perfluorooctanesulfonic acid (PFOS) and perfluorooctanoic acid (PFOA) defluorination, such as those that incorporate hydrated electrons, sulfate, peroxide, and metal catalysts. Bioremediation techniques are also discussed, namely the laccase and horseradish peroxidase systems. The redox potential of known reactants and enzymatic radicals/metal-complexes are then considered and compared to potential enzymes for degrading PFAS. The molecular structure and reaction cycle of prospective enzymes are explored. Current knowledge and techniques of enzyme design, particularly radical-generating enzymes, and application are also discussed. Finally, potential routes for bioengineering enzymes to enable or enhance PFAS remediation are considered as well as the future outlook for computational exploration of enzymatic in situ bioremediation routes for these highly persistent and globally distributed contaminants

Assessing antibiotic sorption in soil: a literature review and new case studies on sulfonamides and macrolides

The increased use of veterinary antibiotics in modern agriculture for therapeutic uses and growth promotion has raised concern regarding the environmental impacts of antibiotic residues in soil and water. The mobility and transport of antibiotics in the environment depends on their sorption behavior, which is typically predicted by extrapolating from an experimentally determined soil-water distribution coefficient (K(d)). Accurate determination of K(d) values is important in order to better predict the environmental fate of antibiotics. In this paper, we examine different analytical approaches in assessing K(d) of two major classes of veterinary antibiotics (sulfonamides and macrolides) and compare the existing literature data with experimental data obtained in our laboratory. While environmental parameters such as soil pH and organic matter content are the most significant factors that affect the sorption of antibiotics in soil, it is important to consider the concentrations used, the analytical method employed, and the transformations that can occur when determining K(d) values. Application of solid phase extraction and liquid chromatography/mass spectrometry can facilitate accurate determination of K(d) at environmentally relevant concentrations. Because the bioavailability of antibiotics in soil depends on their sorption behavior, it is important to examine current practices in assessing their mobility in soil

Co-occurrence of antimicrobials and metals as potential drivers of antimicrobial resistance in swine farms

The application of animal manures to cropland is an important nutrient recycling strategy in many parts of the world. Commonly, aggregated manure wastes contain chemical stressors including veterinary antimicrobials, heavy metals, and antimicrobial resistance genes (ARGs) that can stimulate the development and proliferation of antimicrobial resistance (AMR). While the presence of antimicrobials in manure is well-documented, the co-occurrence of other potentially impactful chemical stressors in swine manure remains underreported. This study quantifies and analyzes correlations between antimicrobials, metals, and certain ARGs present in manure samples from swine farms in Iowa, United States. Relationships between chemical stressors and different stages of swine production or feed composition are also investigated. Results revealed substantial levels of tetracyclines [up to 1,260 µg g−1 dry weight (d.w.) of manure for oxytetracycline] detected in all samples. Tiamulin, two ionophores (monensin and lasalocid), and one macrolide (tilmicosin) were detected at maximum class concentrations of 9.4, 0.547, and 0.472 µg g−1 d.w., respectively. The median relative abundances of ermB and tetM were 0.13 and 0.17 copies g−1 wet weight (w.w.) manure (normalized to 16S gene), respectively. Additionally, high levels of copper (Cu), iron (Fe), and zinc (Zn) were detected in all samples, with maximum concentrations of 887, 1,900, and 2,100 µg g−1 d.w., respectively. Notably, uranium (U) was detected in 11 samples, at concentrations up to 0.77 µg g−1. A global analysis of AMR-stressor relationships using Spearman’s rank correlation indicates Cu, and Ba are the most positively and significantly correlated with cytotoxic anhydrotetracycline (ATC) and/or anhydrochlortetracycline (ACTC) concentrations in all tested facilities (Cu-ATC: ρ = 0.67, p = 0.0093; Cu-ACTC: ρ = 0.75, p = 0.0022; Ba-ATC: ρ = 0.84, p = 0.0002). Interestingly, ermB and tetM genes were strongly, positively correlated to each other (ρ = 0.92, p < 0.0001), suggesting possible co-selection, despite the absence of correlation between ARGs and tetracycline concentrations. This study demonstrates the complexity of interactions between antimicrobials, metals, and ARGs in multiple manure storage pits prior to cropland application.This article is published as Congilosi, Jena L., Joshua S. Wallace, Timothy P. Neher, Adina Howe, Michelle L. Soupir, and Diana S. Aga. "Co-occurrence of antimicrobials and metals as potential drivers of antimicrobial resistance in swine farms." Frontiers in Environmental Science 10 (2022): 1018739. doi: https://doi.org/10.3389/fenvs.2022.1018739. © 2022 Congilosi, Wallace, Neher, Howe, Soupir and Aga. This is an open access article distributed under the terms of the Creative Commons Attribution License (https://creativecommons.org/licenses/by/4.0/)

Selective P2X7 receptor antagonists for chronic inflammation and pain

ATP, acting on P2X7 receptors, stimulates changes in intracellular calcium concentrations, maturation, and release of interleukin-1β (IL-1β), and following prolonged agonist exposure, cell death. The functional effects of P2X7 receptor activation facilitate several proinflammatory processes associated with arthritis. Within the nervous system, these proinflammatory processes may also contribute to the development and maintenance of chronic pain. Emerging data from genetic knockout studies have indicated specific roles for P2X7 receptors in inflammatory and neuropathic pain states. The discovery of multiple distinct chemical series of potent and highly selective P2X7 receptor antagonists have enhanced our understanding of P2X7 receptor pharmacology and the diverse array of P2X7 receptor signaling mechanisms. These antagonists have provided mechanistic insight into the role(s) P2X7 receptors play under pathophysiological conditions. In this review, we integrate the recent discoveries of novel P2X7 receptor-selective antagonists with a brief update on P2X7 receptor pharmacology and its therapeutic potential

Actin-interacting and flagellar proteins in Leishmania spp.: Bioinformatics predictions to functional assignments in phagosome formation

Several motile processes are responsible for the movement of proteins into and within the flagellar membrane, but little is known about the process by which specific proteins (either actin-associated or not) are targeted to protozoan flagellar membranes. Actin is a major cytoskeleton protein, while polymerization and depolymerization of parasite actin and actin-interacting proteins (AIPs) during both processes of motility and host cell entry might be key events for successful infection. For a better understanding the eukaryotic flagellar dynamics, we have surveyed genomes, transcriptomes and proteomes of pathogenic Leishmania spp. to identify pertinent genes/proteins and to build in silico models to properly address their putative roles in trypanosomatid virulence. In a search for AIPs involved in flagellar activities, we applied computational biology and proteomic tools to infer from the biological meaning of coronins and Arp2/3, two important elements in phagosome formation after parasite phagocytosis by macrophages. Results presented here provide the first report of Leishmania coronin and Arp2/3 as flagellar proteins that also might be involved in phagosome formation through actin polymerization within the flagellar environment. This is an issue worthy of further in vitro examination that remains now as a direct, positive bioinformatics-derived inference to be presented

Global disparities in surgeons’ workloads, academic engagement and rest periods: the on-calL shIft fOr geNEral SurgeonS (LIONESS) study

: The workload of general surgeons is multifaceted, encompassing not only surgical procedures but also a myriad of other responsibilities. From April to May 2023, we conducted a CHERRIES-compliant internet-based survey analyzing clinical practice, academic engagement, and post-on-call rest. The questionnaire featured six sections with 35 questions. Statistical analysis used Chi-square tests, ANOVA, and logistic regression (SPSS® v. 28). The survey received a total of 1.046 responses (65.4%). Over 78.0% of responders came from Europe, 65.1% came from a general surgery unit; 92.8% of European and 87.5% of North American respondents were involved in research, compared to 71.7% in Africa. Europe led in publishing research studies (6.6 ± 8.6 yearly). Teaching involvement was high in North America (100%) and Africa (91.7%). Surgeons reported an average of 6.7 ± 4.9 on-call shifts per month, with European and North American surgeons experiencing 6.5 ± 4.9 and 7.8 ± 4.1 on-calls monthly, respectively. African surgeons had the highest on-call frequency (8.7 ± 6.1). Post-on-call, only 35.1% of respondents received a day off. Europeans were most likely (40%) to have a day off, while African surgeons were least likely (6.7%). On the adjusted multivariable analysis HDI (Human Development Index) (aOR 1.993) hospital capacity &gt; 400 beds (aOR 2.423), working in a specialty surgery unit (aOR 2.087), and making the on-call in-house (aOR 5.446), significantly predicted the likelihood of having a day off after an on-call shift. Our study revealed critical insights into the disparities in workload, access to research, and professional opportunities for surgeons across different continents, underscored by the HDI

Analytical applications of immunoassays in environmental and agricultural chemistry: Study of the fate and transport of herbicides

Dissertation (Ph.D.)--University of Kansas, Chemistry, 1995.Enzyme-linked immunosorbent assay (ELISA) has become popular recently in the analysis of herbicides in many environmental samples. In this study, interference due to the presence of other herbicides and their degradation products, and other factors that may potentially affect the performance of ELISAs, such as percent dissolved organic matter and solvents used for sample extraction, were investigated. ELISA's for the most widely used herbicides, such as atrazine, alachlor, metolachlor, and 2,4-D, were used to analyze samples from various sources which are representative of the natural environment. These include samples from lakes, rivers, reservoirs, precipitation, and ground-water wells. Selected samples were confirmed by gas chromatography/mass spectrometry or by high-performance liquid chromatography to show the validity of the immunoassay results. Solid-phase extraction (SPE) was used as a sample pre-concentration step to improve the detection limit of the ELISA for the measurement of low-levels of atrazine in rain and pristine water samples. Also, an SPE method was used to effectively separate alachlor and the alachlor ethanesulfonic acid metabolite (ESA) in order to quantitatively measure the concentration of each compound using the same polyclonal antibodies which recognize both alachlor and ESA. Polyclonal antibodies were produced against 2,4-D by immunizing rabbits. The polyclonal antibodies generated were used for ELISA and for preparation of immunoaffinity chromatography columns. The use of SPE as a preconcentration step for low-level analysis of 2,4-D was not successful because of the simultaneous isolation of humic substances which interfered with both ELISA and HPLC analysis. The use of immunoaffinity columns for sample preparation of water samples containing 2,4-D reduced the problems associated with humic substances. This research also identified important degradation products of the widely used chloroacetanilide herbicides, alachlor and metolachlor. It was shown that metolachlor degrades to a metolachlor ESA metabolite, which is analogous to the alachlor ESA. Using the combination of analytical methods developed above, the relative mobility and persistence of both the parent herbicides and metabolites were cost-effectively determined in an experimental field plots. In addition, the leaching potentials of the four chloroacetanilide herbicides, acetochlor, alachlor, metolachlor, and propachlor were compared

Occurrence of sulfonamide antimicrobials in private water wells in Washington County, Idaho, USA

County (Weiser, Idaho) were collected to assess the impact of a nearby confined animal feeding operation (CAFO) on the quality of the local groundwater. All six samples were found contaminated by two veterinary antimicrobials, sulfamethazine (at concentrations from 0.076 to 0.22 μg/l) and sulfadimethoxine (at concentrations from 0.046 to 0.068 μg/l). These groundwater samples also contained elevated concentrations of nitrate and ammonium. Three of the sampled wells have nitrate levels that exceeded the maximum contaminant level set by the US Environmental Protection Agency for drinking water, with nitrate concentration as high as 39.1 mg/l. All but one well showed nitrate, which instead contained ammonium at 1.22 mg/l. Analysis of the nitrate and ammonium in these samples by isotopic ratio mass spectrometry indicated δ15N characteristic of an animal or human waste source. Results from this study underscore the role of CAFO as an important source of antibiotic contamination of groundwater