Chitinase-Induced Airway Hyperreactivity and Inflammation in a Mouse Model of Nonallergic Asthma.

INTRODUCTION Environmental exposure to mites and fungi has been proposed to critically contribute to the development of IgE-mediated asthma. A common denominator of such organisms is chitin. Human chitinases have been reported to be upregulated by interleukin-13 secreted in the context of Th2-type immune responses and to induce asthma. We assessed whether chitin-containing components induced chitinases in an innate immune-dependent way and whether this results in bronchial hyperresponsiveness. MATERIALS AND METHODS Monocyte/macrophage cell lines were stimulated with chitin-containing or bacterial components in vitro. Chitinase activity in the supernatant and the expression of the chitotriosidase gene were measured by enzyme assay and quantitative PCR, respectively. Non-sensitized mice were stimulated with chitin-containing components intranasally, and a chitinase inhibitor was administered intraperitoneally. As markers for inflammation leukocytes were counted in the bronchoalveolar lavage (BAL) fluid, and airway hyperresponsiveness was assessed via methacholine challenge. RESULTS We found both whole chitin-containing dust mites as well as the fungal cell wall component zymosan A but not endotoxin-induced chitinase activity and chitotriosidase gene expression in vitro. The intranasal application of zymosan A into mice led to the induction of chitinase activity in the BAL fluid and to bronchial hyperresponsiveness, which could be reduced by applying the chitinase inhibitor allosamidin. DISCUSSION We propose that environmental exposure to mites and fungi leads to the induction of chitinase, which in turn favors the development of bronchial hyperreactivity in an IgE-independent manner

Microstructural analyses of Cr(VI) speciation in chromite ore processing Residue (COPR)

The speciation and distribution of Cr(VI) in the solid phase was investigated for two types of chromite ore processing residue (COPR) found at two deposition sites in the United States: gray-black (GB) granular and hard brown (HB) cemented COPR. COPR chemistry and mineralogy were investigated using micro-X-ray absorption spectroscopy and micro-X-ray diffraction, complemented by laboratory analyses. GB COPR contained 30percent of its total Cr(VI) (6000 mg/kg) as large crystals(>20 ?m diameter) of a previously unreported Na-rich analog of calcium aluminum chromate hydrates. These Cr(VI)-rich phases are thought to be vulnerable to reductive and pH treatments. More than 50percent of the Cr(VI) was located within nodules, not easily accessible to dissolved reductants, and bound to Fe-rich hydrogarnet, hydrotalcite, and possibly brucite. These phases are stable over a large pH range, thus harder to dissolve. Brownmilleritewasalso likely associated with physical entrapment of Cr(VI) in the interior of nodules. HB COPR contained no Cr(VI)-rich phases; all Cr(VI) was diffuse within the nodules and absent from the cementing matrix, with hydrogarnet and hydrotalcite being the main Cr(VI) binding phases. Treatment ofHBCOPRis challenging in terms of dissolving the acidity-resistant, inaccessible Cr(VI) compounds; the same applies to ~;;50percent of Cr(VI) in GB COPR

Thermodynamic and Kinetic Modeling of the Lime–Kaolinite System

A thermodynamic and kinetic model of kaolinite mixed with 5% lime was developed in this study in order to inform the long-term prediction of the system composition and its influence on the geotechnical properties of lime-stabilized clays. For model calibration, pore solution analysis of lime–kaolinite-compacted monoliths was performed for up to 2 years of curing time. The model showed that there are three stages in the evolution of the pozzolanic reactions that correspond to a progressive decrease in the rate of kaolinite dissolution. In the first stage (0–180 days of curing), portlandite is consumed rapidly, and kaolinite dissolution proceeds at the highest rate. From the model prediction, the phase assemblage during this stage is amorphous jennite, C4AH13, and SO4-AFm, which control Al and Si in solution at very low values and result in rapid strength development. In the next stage (180–360 days), portlandite is consumed and kaolinite dissolution slows down. Si and Al in solution increase rapidly, and the phase assemblage shows transformation to stratlingite first and then a small amount of gibbsite and tobermorite-II also starts forming. The last stage is marked by a further decrease in the dissolution rate and transformation of stratlingite to tobermorite-II and gibbsite, with every component in the solution plateauing except Si, which is predicted by the model to increase. The phase transformation is related to a reduction in strength from 360 to 720 days of curing. The model also predicts a last drop in pH and Al when stratlingite is completely depleted and equilibrium is reached, which was not observed in the experiments terminated at 720 days

Aerobic Cr(VI) Reduction by Bacteria in Culture and Soil Conditions

We compared the performance of aerobic Cr(VI)-reducing bacteria isolated from Cr(VI)-contaminated soil in pure and mixed cultures of five isolated strains. The mixed culture had increased reduction rates compared to individual cultures. Cr(VI) reduction was observed in sterile soil inoculated with Pseudomonas fluorescens and in non-sterile soil with and without inoculation with P. fluorescens at initial pore water concentrations up to 1,600 mg Cr(VI)/L, whereas in culture the maximum inhibitory concentration was 500 mg Cr(VI)/L. Linear rates of Cr(VI) reduction in non-sterile soil amended with peptone were ~5 to 8 times higher than those observed in the mixed culture. Inoculation of non-sterile soil with P. fluorescens did not further enhance Cr(VI) reduction rates. Our results indicate that evaluation of Cr(VI) reduction capacity in Cr(VI)-contaminated soil for in-situ bioremediation purposes should not be done solely in pure culture. Although the latter may be used initially to assess the effects of process parameters (e.g., pH, temperature), the rate and extent of Cr(VI) reduction should be determined in soil for bioremediation design purposes. © 2013 Copyright Taylor and Francis Group, LLC

Green Dental Environmentalism among Students and Dentists in Greece

Ηuman sustainability in dental enterprises, as in every workplace, is connected to air and water quality, eco-friendly and naturally designed working spaces, and the culture of the 4Rs. The purpose of this study was to assess pro-environmental behavior, as well as knowledge of preferences for circular economies and green building construction, among a sample of dental students and dentists in Greece. We further assessed the factors influencing their choices. Students (N1 = 93) and dentists (N2 = 126) filled in e-questionnaires from April to December 2022. The data revealed that both students and dentists lack knowledge about the circular economy (N1 = 67.74%, N2 = 68.25%), EU regulations on amalgam disposal (N1 = 64.51%, N2 = 58.73%), and plastic recycling (N1 = 76.34%, N2 = 76.98%); meanwhile, they do recycle at home (N1 = 80.64%, N2 = 82.54%) and have participated in voluntary environmental initiatives (N1 = 58.06%, N2 = 66.66%). Gender influences the importance of factors related to green dental practices, with women students being more likely to agree that increased costs for network changes (p = 0.02) and poor wastewater management (p = 0.01) are significant. Students from urban areas are more likely to give positive answers to questions related to the lack of state financial support (p = 0.02), low levels of green design in buildings (p = 0.03), the negligible direct financial benefits of green dental offices (p = 0.04), the negligible reputational benefits of green dental offices (p = 0.02), and the lack of continuing education training seminars on green dentistry (p = 0.05). For dentists, no significant relationships were observed, except for a weak positive relationship for the increases in costs due to changes related to utility networks (p = 0.08), while increases in waste energy (p = 0.12) and the waste of dental materials (p = 0.19) seemed significant only for dentists in urban areas. Women dentists were more likely to answer positively regarding wasting energy (p = 0.024) and the use of unapproved disinfection products (p = 0.036). The findings contribute ideas and solutions for green dental practice buildings and sustainable behaviors through educational activities and regarding the social aspects of factors such as age, experience in dentistry, gender, and urbanism. This study also provides a basis for future multi-disciplinary research on dental quality assurance, the psychology of environmentalism, economics, and behavioral science in dentistry

Investigation of Chromate Coordination on Ferrihydrite by in Situ ATR-FTIR Spectroscopy and Theoretical Frequency Calculations

Chromate mobility, reactivity, and bioavailability in soil environments are affected by adsorption reactions on iron oxide minerals, but the adsorption mechanisms remain controversial. In this study, we employed in situ attenuated total reflectance Fourier transform infrared spectroscopy and theoretical frequency calculations to characterize chromate adsorption on 2-line ferrihydrite. The effects of pH, aqueous chromate concentration, ionic strength, and deuterium exchange were investigated. Results suggest the formation of monodentate and bidentate surface complexes. It was determined that monodentate complexes are dominant at low surface coverage and pH ≥ 6.5 and that bidentate complexes form at high surface coverage and pH < 6. Deuterium exchange experiments indicated that the inner-sphere complexes are not protonated. Difference spectra revealed that monodentate complexes are particularly susceptible to ionic strength effects under acidic conditions

Mechanisms of Chromate, Selenate, and Sulfate Adsorption on Al-Substituted Ferrihydrite: Implications for Ferrihydrite Surface Structure and Reactivity

Ferrihydrite is a nanocrystalline Fe (hydr)­oxide and important sink for environmental contaminants. Although Fe (hydr)­oxides are rarely pure in natural systems, little is known about the effects of structural impurities such as Al on the surface properties and reactivity of ferrihydrite. In this study, we characterized the adsorption mechanisms of chromate, selenate, and sulfate on Al-substituted ferrihydrite (0, 6, 12, 18, and 24 mol % Al) using in situ attenuated total reflection Fourier transform infrared spectroscopy. Spectral data sets recorded as a function of pH were processed using a multivariate curve resolution technique to identify which types of surface species form and to generate their concentration profiles as a function of pH and Al content. Results show a significant increase in relative fraction of outer-sphere complexes for all three oxyanions with increasing Al substitution. In addition, the effect of Al substitution is found to be mechanism-specific in the case of chromate, with bidentate complexes disproportionately suppressed over monodentate complexes at higher Al contents. Overall, our findings have important implications for the fate of chromate, selenate, and sulfate in subsurface environments and offer new insight into the surface reactivity of Al–ferrihydrite

Density functional theory modeling of chromate adsorption onto ferrihydrite nanoparticles

Abstract Density functional theory (DFT) calculations were performed on a model of a ferrihydrite nanoparticle interacting with chromate ($${\text{CrO}}_{4}^{2 - }$$ CrO42- ) in water. Two configurations each of monodentate and bidentate adsorbed chromate as well as an outer-sphere and a dissolved bichromate ($${\text{HCrO}}_{4}^{ - }$$ HCrO4- ) were simulated. In addition to the 3-D periodic planewave DFT models, molecular clusters were extracted from the energy-minimized structures. Calculated interatomic distances from the periodic and cluster models compare favorably with Extended X-ray Absorption Fine Structure spectroscopy values, with larger discrepancies seen for the clusters due to over-relaxation of the model substrate. Relative potential energies were derived from the periodic models and Gibbs free energies from the cluster models. A key result is that the bidentate binuclear configuration is the lowest in potential energy in the periodic models followed by the outer-sphere complex. This result is consistent with observations of the predominance of bidentate chromate adsorption on ferrihydrite under conditions of high surface coverage (Johnston Environ Sci Technol 46:5851–5858, 2012). Cluster models were also used to perform frequency analyses for comparison with observed ATR FTIR spectra. Calculated frequencies on monodentate, bidentate binuclear, and outer-sphere complexes each have infrared (IR)-active modes consistent with experiment. Inconsistencies between the thermodynamic predictions and the IR-frequency analysis suggest that the 3-D periodic models are not capturing key components of the system that influence the adsorption equilibria under varying conditions of pH, ionic strength and electrolyte composition. Model equilibration via molecular dynamics (MD) simulations is necessary to escape metastable states created during DFT energy minimizations based on the initial classical force field MD-derived starting configurations

MOESM1 of Density functional theory modeling of chromate adsorption onto ferrihydrite nanoparticles

Additional file 1: Table S1. Cr K-edge fitting results for the local structure of chromate adsorbed to ferrihydrite based on the monodentate and bidentate two-complex model. The fitting was evaluated with a reduced χ2 = 7.32 and a goodness of fit (R-factor) of 0.009. Table S2. Frequency correlations with various exchange correlation functionals using the 6-311+G(d,p) basis set. Note values are not listed for the outer-sphere models because calculated frequencies only match with one observed frequency near 955 cm−1