Mutation-driven resistance development in wastewater E. coli upon low-level cephalosporins: Pharmacophore contribution and novel mechanism.

Cephalosporins have been widely applied in clinical and veterinary settings and detected at increasing concentrations in water environments. They potentially induce high-level antibiotic resistance at environmental concentrations. This study characterized how typical wastewater bacteria developed heritable antibiotic resistance under exposure to different cephalosporins, including pharmacophore-resistance correlation, resistance mechanism, and occurrence of resistance-relevant mutations in different water environments. Wastewater-isolated E. coli JX1 was exposed to eight cephalosporins individually at 25 µg/L for 60 days. Multidrug resistance developed and diverse mutations arose in selected mutants, where a single mutation in ATP phosphoribosyltransferase encoding gene (hisG) resulted in up to 128-fold increase in resistance to meropenem. Molprint2D pharma RQSAR analysis revealed that hydrogen-bond acceptors and hydrophobic groups in the R1 and R2 substituents of cephalosporins contributed positively to antibiotic resistance. Some of these pharmacophores may persist during bio- or photo-degradation in the environment. hisG mutation confers a novel resistance mechanism by inhibiting fatty acid degradation, and its variants were more abundant in water-related E. coli (especially in the effluent of wastewater treatment plants) compared with those in non-water environments. These results suggest that specific degradation of particular pharmacophores in cephalosporins could be useful for controlling resistance development, and mutations in previously unreported resistance genes (e.g., hisG) can lead to overlooked antibiotic resistance risks in water environments.

Remediation of organophosphorus pesticide polluted soil using persulfate oxidation activated by microwave.

Contaminated sites from pesticide industry have attracted global concern due to the characteristics of organic pollution with high concentrations and complete loss of habitat conditions. Remediation of organophosphorus pesticide polluted soil using microwave-activated persulfate (MW/PS) oxidation was investigated in this study, with parathion as the representative pesticide. Approximately 90 % of parathion was degraded after 90 min of MW/PS oxidation treatment, which was superior to those by single PS or MW treatment. Relatively greater performances for parathion degradation were obtained in a relatively larger PS dosage, higher microwave temperature, and lower organic matter content. Appropriate soil moisture favored parathion degradation in soil. SO4-, OH, O2-, and 1O2 generated in the MW/PS system all contributed to parathion degradation. Multiple spectroscopy analyses indicated that PO and PS bonds in parathion were destroyed after MW/PS oxidation, accompanied by generation of hydroxylated and carbonylated byproducts. The soil safety after parathion degradation was assessed via model prediction. Furthermore, MW/PS oxidation also exhibited great performance for degradation of other organophosphorus pesticides, including ethion, phorate, and terbufos.

[Effect of pulp revascularization on CCL21, IFN-γ-inducible protein 10 in chronic periapical periodontitis].

PURPOSE: To investigate the effect of pulp revascularization on the levels of CCL21 and IFN-γ-inducible protein 10（IP-10）in chronic periapical periodontitis. METHODS: One hundred patients with chronic periapical periodontitis treated from September 2018 to May 2019 were selected as the research subjects. They were divided into two groups by using random number table method. The patients in both groups were taken cone-beam CT(CBCT) film for filing before operation. Patients in the experimental group were treated by pulp revascularization, while patients in the control group were treated by apexification. The level of CCL21 and IP-10 was measured within 4 weeks. The results of operation, the ratio of crown to root and the thickness of root canal wall were analyzed. Statistical analysis of the data was conducted with SPSS 25.0 software package. RESULTS: CCL21 and IP-10 levels of the two groups increased in the course of 1-3 weeks, but decreased after 4 weeks. CCL21 levels were significantly different at 2 weeks, 3 weeks and 4 weeks(P<0.05), but there was no significant difference at one week(P<0.05). There was no significant difference in IP-10 level between the two groups at 1, 2 and 3 weeks of treatment(P<0.05), but there was significant difference at 4 weeks of treatment (P<0.05). The success rate of the experimental group was 90% and that of the control group was 50%，there was a significant difference between the two groups(P<0.05). There was no significant difference in the ratio of crown to root and the thickness of root canal wall between the two groups(P<0.05). CONCLUSIONS: For chronic periapical diseases, pulp revascularization, apical induction can promote the secretion of chemokines CCL21 and IP-10 in the early stage of treatment, the level of CCL21 changes greatly in the early stage of treatment, while changes of IP-10 can be seen in the later stage.

Non-thermal plasma oxidation of Cu(II)-EDTA and simultaneous Cu(II) elimination by chemical precipitation.

Cu2+ readily complexes with ethylenediaminetetraacetic acid (EDTA) to form a heavy metal complex (Cu-EDTA) that is typical in the effluents from mining and electroplating industries. It was difficult for the classical alkaline precipitation method to eliminate the heavy metal complex due to the strong bonding ability between Cu(II) and EDTA. Cu(II) release and removal performance after Cu-EDTA decomplexation in a non-thermal plasma oxidation system was carried out in this study. The removal process was characterized by chemical oxygen demand, total organic carbon, atomic force microscopy, and electroconductivity analysis. The toxicity effect of the treated Cu-EDTA solution was also tested by photobacterium bioassay. The experimental results showed that 80.2% of Cu was released and removed within 60 min of the non-thermal plasma treatment/alkaline precipitation. Relatively higher energy input, lower Cu-EDTA concentration, and acidic conditions were necessary to obtain greater Cu release and removal performance, and there existed an appropriate air flow rate for high-efficient Cu release and removal. O2-, OH, 1O2, and O3 were the main active substances leading to Cu2+ release. Its residual toxicity to P.phosphoreum sp.-T3 was significantly reduced after treatment.