BACKGROUND:Most of the silver coating materials prepared using active screen plasma technology in the past do not involve the nanotechnology field.The formed silver coating is in a"thin film"form,which is coated on the surface of the substrate,and the distribution of silver particles on the surface is uneven.Its long-term antibacterial ability is challenged. OBJECTIVE:To prepare nano silver coatings capable of being"buried"within stainless steel(SS)substrates using active screen plasma surface modification(ASPSM)and to observe antibacterial activity. METHODS:The nano-silver coating was prepared by ASPSM technique on stainless steel substrate.Three groups of coating samples were prepared by adjusting the bombardment time(1,2,and 4 hours),which were denoted as 1 h-Ag-ASPSM@SS,2 h-Ag-ASPSM@SS and 4 h-Ag-ASPSM@SS,respectively.The antibacterial activity of the coatings was analyzed by antibacterial ring test and Gram staining.The antibiotic coating samples of gentamicin combined with vancomycin were prepared by using stainless steel as substrate and were recorded as ACNs.Stainless steel,2 h-Ag-ASPSM@SS,and ACNs were inserted into Staphylococcus aureus or Pseudomonas aeruginosa suspension,respectively.The long-acting(84 days)antibacterial activity of the samples was analyzed by coating plate method.Bone marrow mesenchymal stem cells were co-cultured with stainless steel,2 h-Ag-ASPSM@SS,and ACNs,respectively.CCK-8 assay,dead/alive staining,and lactate dehydrogenase activity of cell supernatant were detected.Stainless steel,2 h-Ag-ASPSM@SS,and ACNs were taken after continuous exposure to Staphylococcus aureus suspension for 12 weeks.The amount of residual viable bacteria on the surface of the material was evaluated by spread plate method.Vancomycin drug sensitive disk method was used to evaluate the resistance of residual live bacteria on the surface of materials. RESULTS AND CONCLUSION:(1)With increasing bombardment time,the diameter of nano silver on the sample surface and the silver content in the coating gradually increased.Among them,the 2 h-Ag-ASPSM@SS exhibited the highest surface silver content while forming uniformly spherical nanoparticles.(2)Antibacterial ring test and Gram staining results demonstrated that compared with 1 h-Ag-ASPSM@SS and 4 h-Ag-ASPSM@SS,the 2 h-Ag-ASPSM@SS exhibited better inhibitory effect on Staphylococcus aureus and pseudomonas aeruginosa.After co-culturing with bacteria for 42 and 84 days,the number of viable bacteria on the spread plate method was significantly lower in the 2 h-Ag-ASPSM@SS group compared to the stainless steel and ACNs groups.After co-culturing with Staphylococcus aureus for 84 days and Pseudomonas aeruginosa for 42 days,the number of viable bacteria on the surface of the eluate from the ACNs group was higher than that of the stainless steel group.(3)CCK-8 assay,live/dead staining and lactate dehydrogenase activity of cell supernatant displayed that 2 h-Ag-ASPSM@SS did not have obvious cytotoxicity.ACNs showed obvious cytotoxicity.(4)After co-culture with Staphylococcus aureus for 12 weeks,the residual viable bacteria on the surface of 2 h-Ag-ASPSM@SS group was less than that of stainless steel group,and the residual viable bacteria on the surface of the ACNs group was more than that of stainless steel group.Compared with the stainless steel group,the sensitivity to vancomycin was significantly decreased in the ACNs group(P＜0.001),and there was no significant change in sensitivity to vancomycin in 2 h-Ag-ASPSM@SS group(P＞0.05).(5)The above results indicate that the silver nanoparticle coated stainless steel greatly improves the deposition efficiency of silver nanoparticles on the stainless steel surface and has long-lasting antibacterial properties and good cell compatibility.

Objective To investigate whether curcumin alleviates septic lung injury by inhibiting ferroptosis through modulating the TXNIP/TRX-1/GPX4 pathway.Methods Male C57BL/6 mice were randomly divided into Sham group,cecal ligation puncture(CLP)-induced sepsis group,CLP with curcumin treatment(50,100,and 200 mg/kg)groups,and CLP with both curcumin(200 mg/kg)and TRX-1 inhibitor PX-12(25 mg/kg)treatment group.Inflammatory factors,MDA,MPO,and GSH levels in the lung tissue of the mice were detected.Beas-2B cells stimulated with lipopolysaccharide(LPS;1 μg/mL)were treated with 2.5,5,or 10 μmol/L curcumin or with 10 μmol/L curcumin combined with 5 μmol/L PX-12,and the changes in MDA,Fe2+and ROS levels were assessed.Western blotting was performed to detect the protein expressions of TXNIP,TRX-1,GPX4 and X-CT in both the mouse lung tissues and Beas-2B cells.Results The mice with CLP-induced sepsis showed severe lung injury with elevated expressions of IL-6,IL-1β,TNF-α,MDA and MPO and decreased GSH expression.In Beas-2B cells,LPS stimulation significantly increased MDA and Fe2+levels and ROS release,increased TXNIP protein expression,and lowered the protein expression levels of TRX-1,GPX4 and X-CT,and these changes were also observed in the septic mice.Curcumin treatments at different concentrations obviously alleviated lung injury in the septic mice and reduced LPS-induced injury in Beas-2B cells.Curcumin significantly decreased the release of inflammatory factors,MDA and MPO,increased GSH level,lowered Fe2+,MDA and ROS levels,increased TXNIP protein expression,and lowered the protein expressions of TRX-1,GPX4 and X-CT in both septic mouse lung tissues and LPS-stimulated Beas-2B cells.The protective effect of curcumin was effectively blocked by PX-12 treatment.Conclusion Curcumin inhibits ferroptosis and alleviates septic lung injury in mice by elevating TRX-1 and GPX4 and decreasing TXNIP in the lung tissue.

Objective To investigate whether curcumin alleviates septic lung injury by inhibiting ferroptosis through modulating the TXNIP/TRX-1/GPX4 pathway.Methods Male C57BL/6 mice were randomly divided into Sham group,cecal ligation puncture(CLP)-induced sepsis group,CLP with curcumin treatment(50,100,and 200 mg/kg)groups,and CLP with both curcumin(200 mg/kg)and TRX-1 inhibitor PX-12(25 mg/kg)treatment group.Inflammatory factors,MDA,MPO,and GSH levels in the lung tissue of the mice were detected.Beas-2B cells stimulated with lipopolysaccharide(LPS;1 μg/mL)were treated with 2.5,5,or 10 μmol/L curcumin or with 10 μmol/L curcumin combined with 5 μmol/L PX-12,and the changes in MDA,Fe2+and ROS levels were assessed.Western blotting was performed to detect the protein expressions of TXNIP,TRX-1,GPX4 and X-CT in both the mouse lung tissues and Beas-2B cells.Results The mice with CLP-induced sepsis showed severe lung injury with elevated expressions of IL-6,IL-1β,TNF-α,MDA and MPO and decreased GSH expression.In Beas-2B cells,LPS stimulation significantly increased MDA and Fe2+levels and ROS release,increased TXNIP protein expression,and lowered the protein expression levels of TRX-1,GPX4 and X-CT,and these changes were also observed in the septic mice.Curcumin treatments at different concentrations obviously alleviated lung injury in the septic mice and reduced LPS-induced injury in Beas-2B cells.Curcumin significantly decreased the release of inflammatory factors,MDA and MPO,increased GSH level,lowered Fe2+,MDA and ROS levels,increased TXNIP protein expression,and lowered the protein expressions of TRX-1,GPX4 and X-CT in both septic mouse lung tissues and LPS-stimulated Beas-2B cells.The protective effect of curcumin was effectively blocked by PX-12 treatment.Conclusion Curcumin inhibits ferroptosis and alleviates septic lung injury in mice by elevating TRX-1 and GPX4 and decreasing TXNIP in the lung tissue.

Aim To investigate the inhibition role and mechanism of adipose derived mesenchymal stem cell(ADMSC)exosomes(Exo)on adverse ventricular remodeling after myocardial infarction(MI).Methods The chan-ges of autophagy and inflammasomes phenotype of cardiac fibroblasts after H2O2 treatment were observed.MI rats were in-jected with an equal volume of normal saline,adipose derived mesenchymal stem cell exosomes(MSC-Exo)or fibroblast exosomes(MEF-Exo)via a tail vein.The expression of autophagy related 16 like protein 1(ATG16L1),autophagy re-lated protein 7(ATG7)and NOD-like receptor protein 3(NLRP3),inflammatory response,the degree of myocardial fi-brosis,and the cardiac function were observed in different groups.Results After treatment with H2O2 on cardiac fi-broblasts,the expressions of ATG16L1 and ATG7 were significantly decreased(P＜0.001),NLRP3 was significantly in-creased(P＜0.001),and the levels of inflammatory cytokines interleukin-1β(IL-1β)and IL-18 were significantly elevated(P＜0.001).After MI rats were intervened with MSC-Exo,the expressions of autophagy related proteins ATG16L1 and ATG7 were significantly up-regulated(P＜0.001),NLRP3 was significantly down-regulated(P＜0.001),serum IL-1β and IL-18 levels were significantly decreased(P＜0.001),fibrosis-related proteins collagen Ⅰ and Ⅲ were significantly reduced(P＜0.001),myocardial fibrosis was significantly relieved(P＜0.001),and cardiac function was sig-nificantly improved(P＜0.001).Conclusion Adipose derived MSC-Exo play a role in inhibiting adverse ventricular remodeling after MI by regulating the balance of autophagy and NLRP3 inflammasomes.

Objective:To explore the differential expression profile of miRN in the development of diabetes nephropathy (DN), and further explore the mechanism of miR-126-5p involved in high glucose induced injury of renal tubular epithelial cells.Methods:Firstly, we downloaded existing chip data from the Gene Expression Integrated Database (GEO) and used GEO2R, miRanda, gene ontology (GO) analysis, and Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis to mine differential miRNAs. Subsequently, a high glucose induced HK-2 cell injury model was used and divided into three groups: high glucose model group, si-HOTAIR group, and si HOTAIR+ miR-126-5p inhibitor group. The three groups of cells were sequentially transfected with siRNA-NC, siRNA-HOTAIR, and siRNA-HOTAIR+ miR-126-5p mimic, and cultured in a medium containing 60 mmol/L glucose. Flow cytometry was used to detect changes in apoptosis levels in each group, while cell counting kit-8 (CCK-8) was used to detect changes in cell proliferation.Results:Through data mining analysis using GEO, it was found that compared to ordinary mice, DN mice had 74 upregulated miRNAs and 80 downregulated miRNAs in their kidney tissue. Enrichment analysis results showed that miRNAs could target signaling pathways such as Wnt, PKG, MAPK, and Rap1, and miR-126-5p was significantly downregulated. In the high glucose induced HK-2 cell injury model, the experimental results showed that the inhibitory effect on cell proliferation activity was more significant at a high glucose concentration of 60 mmol/L ( P<0.05); High glucose stimulation significantly reduced the expression of miR-126-5p ( P<0.05). The results of flow cytometry showed that compared with the high glucose model group, the apoptosis rate of the si-HOTAIR group significantly decreased ( P<0.05), while the apoptosis rate of the si-HOTAIR+ miR-126-5p inhibitor group significantly increased ( P<0.05). The CCK-8 experiment showed that compared with the high glucose model group, the cell viability of the si-HOTAIR group significantly increased ( P<0.05); The cell viability of the si-HOTAIR+ miR-126-5p inhibitor group was inhibited ( P<0.05). Conclusions:miR-126-5p can inhibit high glucose induced apoptosis in HK-2 cells and protect them.

Objective:To investigate the current situation of medical students' autonomous learning in Guangzhou universities, analyze the main factors that affect medical students' self-regulated learning, and explore the strategy for improving the ability of medical students' self-regulated learning.Methods:A stratified sampling survey was conducted among 2 480 medical students from 6 universities in Guangzhou using the self-designed "Questionnaire on Medical Students' Autonomous Learning". SPSS 22.0 was used for statistical analysis of the collected data.Results:There were statistically significant differences in the frequency of self-regulated and professional learning ( χ2=21.33, P<0.001), the self-regulated learning effectiveness and gender differences ( χ2=4.86, P=0.027), the scholastic year system and self-regulated learning necessity cognition ( χ2=4.65, P=0.031), and the family guidance and the suitability of self-learning method selection ability ( χ2=32.43, P<0.001). Conclusions:The schools, individuals and families jointly influence the self-regulated learning of medical students. The three parties should cooperate with each other to improve the self-regulated learning ability of medical students and cultivate high-quality medical talents with life-long learning ability.

Objective:To prepare 99Tc m-hydrazinonicotinamide(HYNIC)-αCD8/Fab ( 99Tc m-αCD8/Fab), and explore the predictive value of 99Tc m-αCD8/Fab SPECT/CT imaging for the efficacy of anti-programmed death-1 (PD-1) immunotherapy. Methods:The αCD8/Fab was modified with HYNIC- N-hydroxysuccinimide (NHS) and IRDye800-NHS to form HYNIC-αCD8/Fab and IRDye800-αCD8/Fab (Dye-αCD8/Fab), respectively. 99Tc m-αCD8/Fab was prepared in sodium bicarbonate buffer (pH=8.5), with SnCl 2 being used as the reducing agent. The labeling yield and radiochemical purity of 99Tc m-αCD8/Fab and its stability in PBS and fetal bovine serum (FBS) were tested in vitro. The mouse spleen and human peripheral blood lymphocytes were isolated for cell-specific binding and blocking experiments of 99Tc m-αCD8/Fab in vitro. SPECT/CT imaging was used to analyze the specific binding ability of the 99Tc m-αCD8/Fab probe in CT26 colon cancer mouse models (BALB/c). The near infrared fluorescence imaging and SPECT/CT imaging were performed to detect the intra-tumoral CD8 + T cell infiltration after anti-PD-1 therapy in tumor bearing mice, and the results were further verified by HE and immunofluorescence staining. CD8 + T cell depletion study was performed to determine the role of CD8 + T cells in the tumor responses to anti-PD-1 therapy. Two-way analysis of variance was used to compare the data difference. Results:The labeling yield of 99Tc m-αCD8/Fab was 90% with a high radiochemical purity (95%) and good stability in vitro (radiochemical purity still more than 80% after 720 min in PBS and FBS). 99Tc m-αCD8/Fab could specifically bind to mouse CD8 + T cells ((10.30±0.81) percent added radioactive dose (%AD)/10 6 cells), compared with the binding ability in human peripheral blood lymphocytes group and CD8 antibody blocking group ((1.78±0.61) and (1.59±0.25) %AD/10 6 cells; F=10.07, P<0.001). SPECT/CT imaging showed that 99Tc m-αCD8/Fab had markedly higher tumor uptake in the CT26 colon cancer mouse models. Near-infrared fluorescence imaging showed that the tumor uptake of 99Tc m-αCD8/Fab in the responsive group was significantly higher than in the nonresponsive group after anti-PD-1 treatment ((8.9±1.1)% vs (7.1±0.8)%; F=4.69, P=0.024), and SPECT/CT imaging found the similar result. HE and immunofluorescence staining of tumor and lymph nodes showed that the proportion of lymphocyte infiltration was higher in the responsive group. Furthermore, CD8 + T cell depletion significantly reversed the therapeutic effect of anti-PD-1 immunotherapy in tumor-bearing mice. Conclusions:In this study, 99Tc m-αCD8/Fab was successfully obtained. CD8-specific SPECT imaging could sensitively visualize the tumor-infiltrating CD8 + T cells, suggesting the potential application value to predict and evaluate the efficacy of immunotherapy in the clinical settings.

Background The altered expressions of hippocampal N-methyl-D-aspartate (NMDA) receptors induced by benzo[ɑ]pyrene (BaP) causes short-term spatial learning and memory impairment in humans and animals, but whether BaP causes alterations of NMDA receptor subunits in other brain regions and the associated neurotoxic mechanism is still essentially unknown. Objective To observe the mRNA expressions of NR1, NR2A, and NR2B of NMDA receptor subunits in different brain regions in SD rat model with subchronic exposure to BaP, and to provide a basis for in-depth study of the mechanism of BaP-induced neurotoxicity. Methods Forty male SD rats were selected and randomly divided into a control group and 1.00, 2.50, and 6.25 mg·kg⁻¹ BaP exposure groups with 10 rats in each group. The exposure rats received intraperitoneal injection of BaP every other day for 90 d.The average latency to platform, the average total distance, and the duration spent in previous quadrant were measured by the Morris Water Maze. Real-time fluorescence quantitative PCR was used to detect the mRNA expressions of NR1, NR2A, and NR2B in hippocampus, cortex, cerebellum, and striatum of rats. Results The average latency to platform and the average total distance in the 2.50 and 6.25 mg·kg⁻¹ BaP groups were significantly prolonged compared with the control group (P<0.05), and the duration that rats spent in previous quadrant in the 6.25 mg·kg⁻¹ BaP group was significantly shortened (P<0.05). Compared with the control group, the mRNA expressions of NR1 and NR2B in the hippocampus in the 2.50 and 6.25 mg·kg⁻¹ BaP groups were significantly reduced (P<0.05), and the NR2A mRNA expression in the hippocampus in the 6.25 mg·kg⁻¹ BaP group was significantly reduced (P<0.05); the mRNA expressions of NR1 and NR2B in the cortical tissue in the 6.25 mg·kg⁻¹ BaP group were significantly reduced (P<0.05), and the mRNA expression of NR2A in the cortical tissue in the 1.00 mg·kg⁻¹ BaP group was reduced; the mRNA expression of NR2B in the cerebellar tissue in the 6.25 mg·kg⁻¹ BaP group was significantly reduced (P<0.05); there were no differences in the mRNA expressions of NMDA receptor subunits in the striatum tissue (P>0.05). Conclusion Subchronic BaP exposure can cause short-term spatial learning and memory impairment in rats, which may be related to the down-regulation of mRNA expressions of NR1, NR2A, and NR2B in hippocampus, changes of mRNA expressions of NR1, NR2A, and NR2B in cortical area, and the down-regulation of NR2B mRNA expression in cerebellum.

Objective: To describe the epidemiological characteristics of a cluster of COVID-19 cases reported in Baodi district of Tianjin as of 18 February, 2020, which might be associated with the exposure in a local department store, and provide suggestions for prevention and control strategy development. Methods: The basic characteristics, time and area distributions, clinical manifestations, epidemiological history and transmission mode of the COVID-19 cases associated with the department store exposure were analyzed. Results: A total of 40 COVID-19 cases were associated with the department store exposure, accounting for 75.47% of the total confirmed cases (53 cases) reported in Baodi district. The cases were mainly at the age of 60 years or older (35.00%) and farmers (40.00%). The main clinical manifestations included fever (95.00%), cough (35.00%), and diarrhea (15.00%). The proportion of confirmed severe cases was 32.50%. The incidence curve showed that the incidence peak occurred on 31 January, 2020. Among the 40 cases, 6(15.00%) were department store employees, 19(47.50%) were customers and 15(37.50%) were close contacts (secondary cases). The first case occurred on 21 January, 2020, this case was a department store employee who had a purchasing history at whole sale markets in other provinces and cities before the onset, and 3 employees were still on duty after symptom onsets. The median of the incubation period of customer cases was 6 days, and the median of the interval between onset and medical treatment of customer cases was 7 days. Conclusion This was a cluster epidemic of COVID-19, which might be associated with the exposure in the department store. By now, the current prevention and control measures have achieved satisfied effects.

Objective:To analyze the self-efficacy of medical students in independent learning and its influencing factors, and to explore the ways to improve their self-learning ability.Methods:A questionnaire survey was conducted among medical students in 6 medical institutions of higher learning in Guangdong Province. A total of 2 480 questionnaires were issued, and 2 282 were recovered. SPSS 19.0 was used to conduct statistical analysis including Kruskal-Wall test and multiple comparisons.Results:There were 47.72% of the medical students who had a strong autonomous learning drive, and more than half of the medical students had strong autonomous learning ability with strong self-efficacy of independent learning. The influence of family location, family guidance degree and different grades on self-efficacy of medical students was different, and there was no significant difference between 5-year and 8-year clinical medical students in self-efficacy of independent learning.Conclusion:Family factors have a great influence on self-efficacy, and senior medical students have the strong ability of self-learning compared with junior medical students. Therefore, we should give full play to the positive impacts of family and school factors to further improve the independent learning ability and efficiency of medical students.