Search

Hardwood biochar (pyrolyzed at 700 °C), a potential candidate for Hg removal, has been proposed for use as reactive capping mats along groundwater discharge zones or riverbanks to control release of Hg from contaminated riverbank sediments. Frequent flooding and drainage in fluvial settings can influence the effectiveness of remediation systems in contaminated riverbank sediments and floodplain soils. This study evaluated the effectiveness of Hg removal using hardwood biochar under hydrogeochemical conditions representative of those present within a reactive capping mat installed in a fluvial setting. Two sets of treatment columns, containing 50% v.v biochar and quartz sand, were subjected to 100 weekly wetting/drying cycles that included dry air, water-saturated air, and drainage using leachate derived from two source columns as input solutions: 1. Passing simulated acid rain water through floodplain soil, 2. Passing river water through riverbank sediment. In both treatment columns, >80% of the Hg was retained on the biochar without promoting Hg methylation and the release of other unintended dissolved constituents (including N, P, DOC). Results from solidphase extraction analyses suggest that Hg accumulated near the air/biochar-sand interface (0-2 cm) in the treatment columns at low loadings but was present at greater depths at higher loadings. Results of micro X-ray fluorescence (μ-XRF) mapping and micro X-ray absorption near edge structure (μ-XANES) for the biochar collected at depths 0-2 cm in treatment columns suggest retention of Hg-bearing particles derived from riverbank sediment and floodplain soil within the pore structure of the biochar. Sulfur K-edge XANES analysis of the unused biochar and the biochar after treatment suggest formation of Hg complexes on the biochar surface. These results indicate that hardwood biochar is potentially an effective media for application in reactive mats for controlling Hg discharging from contaminated riverbank sediments., (Copyright © 2018 Elsevier B.V. All rights reserved.)

The application of biochar to treat mercury (Hg) in the environment is being proposed on an increasing basis due to its widespread availability and cost effectiveness. However, the efficiency of Hg removal by biochars is variable due to differences in source material composition. In this study, a series of batch tests were conducted to evaluate the effectiveness of sulfurized biochars (calcium polysulfide and a dimercapto-related compound, respectively) for Hg removal; Hg-loaded biochars were then characterized using synchrotron-based techniques. Concentrations of Hg decreased by >99.5% in solutions containing the sulfurized biochars. Sulfur X-ray absorption near-edge structure (XANES) analyses indicate a polysulfur-like structure in polysulfide-sulfurized biochar and a thiol-like structure (shifted compared to dimercapto) in the dimercapto-sulfurized biochar. Micro-X-ray fluorescence (μ-XRF) mapping and confocal X-ray micro-fluorescence imaging (CXMFI) analyses indicate Hg is distributed primarily on the edges of sulfurized biochar and throughout unmodified biochar particles. Hg extended X-ray absorption fine structure (EXAFS) analyses show Hg in enriched areas is bound to chlorine (Cl) in the unmodified biochar and to S in sulfurized biochars. These results indicate that Hg removal efficiency is enhanced after sulfurization through the formation of strong bonds (Hg-S) with S-functional groups in the sulfurized biochars., (Copyright © 2017 Elsevier B.V. All rights reserved.)

Objective: To reveal the involvement of inositol 1,4,5-trisphosphate receptors (IP3R) and ryanodine receptors (RyR) in IL-6 prevention from neuronal apoptosis and necrosis induced by N-methyl-D-aspartate (NMDA)., Methods: Cerebellar granule neurons (CGNs) from 8-day-old rats were exposed to IL-6 for 8 days and then stimulated with NMDA for 30 min. The 2-aminoethoxydiphenyl borate (2-APB) and dantrolene (DAN) were used to antagonize IP3R and RyR, respectively. Anti-gp130 monoclonal antibody (mAb) was employed to neutralize gp130, a 130-kDa signal-transducing β-subunit of IL-6 receptor complex. Neuronal apoptosis and necrosis were determined by TUNEL, fluorometric caspase-3 enzyme activity, annexin V-FITC/PI staining and ELISA. Western blot and real-time PCR measured IP3R1 and RyR2 expression, respectively., Results: IL-6 prevented the elevation of TUNEL-positive cells and caspase-3 expression and activity, and also suppressed the increase in annexin V-FITC/PI-positive cells and DNA- and histone-associated nucleosomes in cultured CGNs evoked by NMDA. These anti-apoptotic and anti-necrotic effects of IL-6 were larger on DAN-treated cells than on 2-APB-exposed neurons, since 2-APB treatment alone significantly inhibited the neuronal apoptosis and necrosis but DAN exposure alone did not alter the apoptosis and necrosis induced by NMDA. In support of these results, IL-6 downregulated IP3R1 but did not affect RyR2 expression. All these IL-6 effects were blocked by anti-gp130 mAb., Conclusion: IL-6 prevention from NMDA-triggered Ca2+-induced Ca2+ release-mediated apoptosis and necrosis in CGNs depends on the inhibition of IP3R channel opening and expression rather than on RyR activity. IL-6 receptor-coupled gp130 signaling mediates this neuroprotection of IL-6 resistance to neuronal apoptosis and necrosis.

Over recent decade, studies have shown that inflammatory reaction characterized mainly by the activation of microglia in the brain is implicated in the pathogenesis and processes of neurodegenerative diseases. Neuroinflammation is a double-edged sword. On the one hand, it induces or aggravates the neurodegeneration in the nervous system, and on the other hand, it favors the recovery of the injured neurons in certain conditions. The activated glial cells release pro-inflammatory cytokines and reactive oxygen species, which mediate the neuroinflammation-induced neurodegenerative diseases. The anti-inflammatory cytokines synthesized by regulatory T cells and neuropeptides secreted by neurons protect the neurons against neuroinflammation, through which neurodegenerative diseases are alleviated.

Objective: Dopamine exists in the immune system and has obvious immunomodulating action. However, receptor mechanism underlying the dopamine immunomodulation remains to be clarified. In the present study, we provide the evidence for existence of dopamine receptor subtypes in T lymphocytes and show the roles of the receptors and the receptor-coupled signaling in mediating the dopamine immunomodulation., Methods: The purified T lymphocytes from the mesenteric lymph nodes of mice were detected for expressions of all five subtypes of dopamine receptor mRNAs by reverse transcription-polymerase chain reaction. Lymphocyte proliferation and production of interferon-γ (IFN-γ) and interleukin-4 (IL-4) in response to concanavalin A (Con A) were measured by colorimetric methyl-thiazole-tetrazolium assay and cytometric bead array, respectively, after the cells were exposed to dopamine D1-like or D2-like receptor agonists and antagonists. Meanwhile, content of cAMP and phosphorylation of cAMP-response element-binding (CREB) in the lymphocytes were examined by 125I-cAMP radioimmunoassay and Western blot assay, respectively., Results: T lymphocytes expressed all the five subtypes of dopamine receptor mRNAs, i.e., D1, D2, D3, D4 and D5 receptors. SKF38393, an agonist of dopamine D1-like receptors (D1 and D5 receptors) only reduced the IFN-γ production, but did not significantly affect the proliferative response, IL-4 production, cAMP content or CREB activation of the lymphocytes. The SKF38393-induced decrease in IFN-γ level was blocked by the D1-like receptor antagonist SCH23390. Quinpirole, an agonist of dopamine D2-like receptors (D2, D3 and D4 receptors) attenuated the lymphocyte proliferation to Con A, and decreased the IFN-γ but increased the IL-4 production. Meanwhile, the quinpirole diminished the cAMP content and the phosphorylated CREB level in the lymphocytes. All the quinpirole-induced changes were reversed by dopamine D2-like receptor antagonist haloperidol., Conclusions: Five dopamine receptor subtypes of the two families, D1-like and D2-like receptors, exist on T lymphocytes of mice. Of the two families, D2-like receptors are more important in mediating modulation of T cell function than D1-like receptors. D2-like receptors are involved in suppression of T helper 1 (Th1) cell function and enhancement of Th2 cell function through negative link to cAMP-CREB pathway.