Connexin 43 hyper-phosphorylation at serine 282 triggers apoptosis in rat cardiomyocytes via activation of mitochondrial apoptotic pathway.

Cx43 is the major connexin in ventricular gap junctions, and plays a pivotal role in control of electrical and metabolic communication among adjacent cardiomyocytes. We previously found that Cx43 dephosphorylation at serine 282 (pS282) caused cardiomyocyte apoptosis, which is involved in cardiac ischemia/reperfusion injury. In this study we investigated whether Cx43-S282 hyper-phosphorylation could protect cardiomyocytes against apoptosis. Adenovirus carrying rat full length Cx43 gene (Cx43-wt) or a mutant gene at S282 substituted with aspartic acid (S282D) were transfected into neonatal rat ventricular myocytes (NRVMs) or injected into rat ventricular wall. Rat abdominal aorta constriction model (AAC) was used to assess Cx43-S282 phosphorylation status. We showed that Cx43 phosphorylation at S282 was increased over 2-times compared to Cx43-wt cells at 24 h after transfection, while pS262 and pS368 were unaltered. S282D-transfected cells displayed enhanced gap junctional communication, and increased basal intracellular Ca2+ concentration and spontaneous Ca2+ transients compared to Cx43-wt cells. However, spontaneous apoptosis appeared in NRVMs transfected with S282D for 34 h. Rat ventricular myocardium transfected with S282D in vivo also exhibited apoptotic responses, including increased Bax/Bcl-xL ratio, cytochrome c release as well as caspase-3 and caspase-9 activities, while factor-associated suicide (Fas)/Fas-associated death domain expression and caspase-8 activity remained unaltered. In addition, AAC-induced hypertrophic ventricles had apoptotic injury with Cx43-S282 hyper-phosphorylation compared with Sham ventricles. In conclusion, Cx43 hyper-phosphorylation at S282, as dephosphorylation, also triggers cardiomyocyte apoptosis, but through activation of mitochondrial apoptosis pathway, providing a fine-tuned Cx43-S282 phosphorylation range required for the maintenance of cardiomyocyte function and survival.

Remediation of lead polluted soil by active silicate material prepared from coal fly ash.

To improve the effect of coal fly ash on the remediation of heavy metal polluted soils, the active silicate material (ASM) was prepared by coal fly ash and the remediation of lead polluted soils by ASM was investigated in this study. To study the reaction mechanism between ASM and Pb(II) in soil, the Pb(II) adsorption by ASM was investigated by a series of batch experiments. The result shows that the maximum adsorption capacity of ASM was 300.62 mg g-1 according to the Langmuir isotherm model. The average adsorption energy obtained from the D-K model revealed that the adsorption process of ASM is the ion-exchange process. To apply the ASM to the remediation of lead polluted soils, the soil stabilization experiment and pot experiment were carried out. The results reveal that ASM can reduce the mobility and bioavailability of lead in the soils by transforming the lead from exchangeable fraction, carbonate fraction and reducible fraction to oxidizable fraction and residual fraction. Moreover, ASM can improve the growth of pakchoi by promoting the production of chlorophyll. Furthermore, ASM can reduce the Pb accumulation of pakchoi by inhibiting the absorption of lead in the roots. It is anticipated that this study can provide a novel active silicate material for the application of coal fly ash in heavy metal pollution treatment.

Cronobacter sakazakii induced sepsis-associated arrhythmias through its outer membrane vesicles.

Sepsis-induced arrhythmia, linked to sudden cardiac death, is associated with gut microbiota, though the exact relationship is unclear. This study aimed to elucidate the relationship between Cronobacter sakazakii (C. sakazakii) and arrhythmia. The relative abundance of C. sakazakii was increased in cecal ligation and puncture (CLP)-induced septic mice. Live C. sakazakii, supernatant, and outer membrane vesicles (OMVs) resulted in premature ventricular beat (PVB), sinus arrhythmia (SA), and increased arrhythmia and mortality in sepsis model through dysregulated ion channel proteins. Moreover, short-chain fatty acids (SCFAs) showed antibacterial effects in vitro. We confirmed sodium acetate (C2) and sodium butyrate (C4) protect from C. sakazakii-induced arrhythmia, and C2 and C4 protected from septic arrhythmia by activating free fatty acid receptor 2 and 3 (FFAR2 and FFAR3) in mice. These findings point to how C. sakazakii's OMVs trigger arrhythmia, and SCFAs may be a treatment for septic arrhythmia.

[Removal of Antimony in Wastewater by Electrochemical Hydride Generation and the Recovery of Antimony].

An electrochemical hydride generation method was developed for the removal of antimony in wastewater. Hydrogen was generated in the electrolysis of water. Hydrogen reacted with Sb and formed stibine, which volatilized from the solution. Then, stibine was heated and decomposed to elemental Sb. Based on these, Sb in wastewater could be removed and recovered. The highest removal of Sb (76.1%) was achieved in acidic solution (pH = 4). The formation of stibine was proven to contribute most significantly (66.2%) to the removal of antimony in the solution, while the electro-deposition and adsorption also made a small contribution. In the treatment, Sb(V) must be pre-reduced to Sb(III) prior to the formation of stibine. Lead, graphite and tungsten were employed as the materials for cathode, and lead electrode was found most suitable for the removal of antimony.

[Leaching experiments on the release of trace elements from tailings of Chashan antimony mine, Guangxi, China].

The leaching of trace elements from tailings of an antimony mine in Guangxi Autonomous Region, China, was investigated through column leaching under wet-dry cycling and complete immersion conditions. Simulated acid rain (pH 4.0-4.4) and river water (pH 8.0) were used as the leaching solution. No matter the simulated acid rain or river water was used, the leachate always showed a slightly alkaline pH between 7.2 and 8.0, suggesting an acid neutralization capacity of the tailing. Compared to As and Pb, Sb was leached out to a much higher extent in this circumstance. Furthermore, Sb release was largely enhanced in wet-dry cycle compared to the complete immersion condition. In contrast, As was leached more readily in the complete immersion condition, and the longer the tailings were immersed in water, the higher the As concentration in the leachate. The leachate on day 5 and day 10 showed 1-2 times higher As concentration as compared with the leachate on day 1 and day 2. The leaching of Mn and Zn by simulated acid rain was much stronger than that by river water, and the release of Mn and Zn was more significantly affected by pH than by O2 (i.e., the difference between the wet-dry cycle and complete immersion condition). Sr showed a high release rate that was not affected by leaching solution or air-exposure condition. Basically, Pb showed a very low leaching potential. In general, an alkaline circumstance combined with wet-dry cycle forms the favorable condition for the release of Sb in the tailings.