Objective To investigate and analyze the occupational stress levels and influencing factors among radiation workers in China, and provide a reference for alleviating occupational stress and promoting mental health. Methods Using the general situation questionnaire, Effort-Reward Imbalance questionnaire, and radiation protection knowledge questionnaire, a convenience sampling method was adopted to investigate the occupational stress of 243 radiation workers in Liaoning, Fujian, Guangdong, and Xinjiang provinces. The independent samples t-test, one-way analysis of variance, chi-square test, and binary logistic regression were used to analyze the influencing factors. Results The average score of Effort-Reward Imbalance was 0.97 ± 0.22, and 100 (41.15%) radiation workers had occupational stress. There were significant differences in the detection rate of occupational stress among radiation workers of different ages, working years in radiation positions, monthly incomes, daily sleep durations, and daily working hours (P < 0.05). Logistic regression analysis identified daily working hours as a factor contributing to occupational stress. Conclusion The occupational stress among radiation workers in China is relatively severe. It is recommended to pay attention to the associated risks and implement targeted intervention measures to reduce the impact of occupational stress.

【Objective】 To investigate the anemia status of infants and toddlers aged 6 - 24 months in Linxia Hui Autonomous Prefecture, Gansu Province, and to comprehensively evaluate the differences in feeding behaviors between anaemic and normal children through the infant and child feeding index (ICFI) and feeding knowledge scores, so as to provide reference for the guidance of infants and young children feeding in ethnic minority areas and the promotion of children′s growth and development. 【Methods】 Taking infants and young children aged 6 - 24 months in Linxia Prefecture as the study subjects, a multi-stage random sampling method was used to select children who met the requirements from 5 townships and 5 villages in 7 counties in 2019 and 2020.Periphral blood samples were collected to test the level of hemoglobin, so as to determine the anemia status.Meanwhile, physical examination was performed and a questionnaire survey of guardians was conducted to analyze the association betweenanaemia and feeding patterns 【Results】 A total of 3 901 infants and children were included in this study, of whom 729 (18.70%) were anaemic, with a mean ICFI score of 12.56±2.70 and a mean feeding knowledge score of 1.97±1.01.There was no statistically significant association of low feeding knowledge score and low ICFI with anaemia after adjusting for confounders (P>0.05), Unqualified meat addition in ICFI was a risk factor for anaemia (OR=1.355, P=0.042), while non-bottle feeding in the past 24 hours (OR=0.762, P=0.021), and breastfeeding in the past 24 hours of infants and toddlers aged 12 - 24 months (OR=0.228, P=0.018) were protective factor for anemia in infants and toddlers aged 12 - 24 months. 【Conclusions】 The average prevalence of anemia in infants and toddlers aged 6 - 24 months in Linxia Hui Autonomous Prefecture of Gansu Province is high, but the level of infant feeding and the level of feeding knowledge of caregivers are low.Early adherence to breastfeeding, timely addition of supplementary food, and more comsumpution of meat for children are conducive to preventing anemia.

Objective To isolate a Acinetobacter baumannii(Ab)phage from underground sewage,study its prop-erties,and to provide a theoretical basis for phage treatment of Ab infection.Methods Double-layer agar tech-nique was used to isolate phages by using Ab GY-6 as the host strain.Biological characterization and therapeutic effect of the phage was tested.Genetic information of the phage was analyzed.Results Ab phage Abgy202162 was isolated.Transmission electron microscopy(TEM)analysis showed that the morphology of Abgy202162 exhibited an icosahedral structure.Biological characteristic analysis showed that the optimal multiplicity of infection was 1,the latent period was 5 min,and the burst size was approximately 520 PFU per cell.In addition,Abgy202162 re-mained stable at different concentrations of chloroform,pH,and temperatures.Sodium dodecyl sulfate-polyacryl-amide gel electrophoresis(SDS-PAGE)analysis showed that it contained 10 proteins with molecular weights ran-ging from 15 to 100 ku.The double-stranded(ds)DNA genome of Abgy202162 consisted of 40 889 bp and its G+C content was 38.85％.It contained 47 open reading frames(ORFs),of which 26 had specific functions,but no virulence related genes or antibiotic resistance genes were found.Phylogenetic analysis showed that Abgy202162 was a new phage in the Autographiviridae family,Beijerinkvirinae subfamily,and Friunavirus genus.Abgy202162 showed the ability to prevent Ab infection in the Galleria mellonella in vivo model.Conclusion The phage Ab-gy202162 has strong environmental tolerance and high safety,indicating its potential as an antibiotic alternative used in the treatment of infections caused by Ab.

Flagella are the main motility structure of Clostridioides difficile that affects the adhesion, colonization, and virulence of C. difficile in the human gastrointestinal tract. The FliL protein is a single transmembrane protein bound to the flagellar matrix. This study aimed to investigate the effect of the FliL encoding gene flagellar basal body-associated FliL family protein (fliL) on the phenotype of C. difficile. The fliL gene deletion mutant (ΔfliL) and its corresponding complementary strains (: : fliL) were constructed using allele-coupled exchange (ACE) and the standard molecular clone method. The differences in physiological properties such as growth profile, antibiotic sensitivity, pH resistance, motility, and spore production ability between the mutant and wild-type strains (CD630) were investigated. The ΔfliL mutant and the : : fliL complementary strain were successfully constructed. After comparing the phenotypes of strains CD630, ΔfliL, and : : fliL, the results showed that the growth rate and maximum biomass of ΔfliL mutant decreased than that of CD630. The ΔfliL mutant showed increased sensitivity to amoxicillin, ampicillin, and norfloxacin. Its sensitivity to kanamycin and tetracycline antibiotics decreased, and the antibiotic sensitivity partially returned to the level of CD630 strain in the : : fliL strain. Moreover, the motility was significantly reduced in the ΔfliL mutant. Interestingly, the motility of the : : fliL strain significantly increased even when compared to that of the CD630 strain. Furthermore, the pH tolerance of the ΔfliL mutant significantly increased or decreased at pH 5 or 9, respectively. Finally, the sporulation ability of ΔfliL mutant reduced considerably compared to the CD630 strain and recovered in the : : fliL strain. We conclude that the deletion of the fliL gene significantly reduced the swimming motility of C. difficile, suggesting that the fliL gene is essential for the motility of C. difficile. The fliL gene deletion significantly reduced spore production, cell growth rate, tolerance to different antibiotics, acidity, and alkalinity environments of C. difficile. These physiological characteristics are closely related to the survival advantage in the host intestine, which is correlated with its pathogenicity. Thus, we suggested that the function of the fliL gene is closely related to its motility, colonization, environmental tolerance, and spore production ability, which consequently affects the pathogenicity of C. difficile.
Humans ; Clostridioides/metabolism* ; Clostridioides difficile/metabolism* ; Bacterial Proteins/metabolism* ; Virulence ; Anti-Bacterial Agents/metabolism*

OBJECTIVE The abnormal amyloid-β(Aβ)and oxidative stress assiociated with the progression of Alzheimer disease(AD).Quercetin has been reported to possess antioxidant and anti-inflammatory properties in neurodegenerative disorders.In this present study,we designed to characterize the mechanisms by which quer-cetin exerts neuroprotective effects in murine neuroblas-toma N2a cells stably expressing human Swedish mutant amyloid precursor protein(N2a/APP).METHODS N2a/APP cells were treated with quercetin at concentrations of 10,20 and 50 μ mol·L-1 for 24 h.Cell viability was examined with CCK-8 assays.The protein levels of ERK1/2 and Akt were detected by Western blotting.Intra-cellular reactive oxygen species(ROS)was detected by a fluorescent probe 2,7-dichlorofluorescein diacetate(DCFH-DA).The mitochondrial membrane potential(Δψ m)in N2a/APP cells was detected by using JC-1 staining method.Immunofluorescence was used to detect the generation of 8-hydroxy-2′-deoxyguanosine(8-OHdG)and 4-hydroxynonenal(4-HNE).RESULTS Quercetin attenuated the enhancement of p-ERK1/2,reductions of p-Akt,and decreased levels of APP expression.More-over,quercetin alleviated loss of mitochondria membrane potential(MMP)since it attenuates these oxidative stress,as reflected in the levels of ROS,4-HNE and 8-OHdG,was elevated in N2a/APP cells and these effects were again ameliorated by quercetin.CONCLUSION Neuroprotection by quercetin in N2a/APP cells involves normalizing the impaired mitochondrial function and reducing oxidative stress via inactivation of the ERK1/2 and activation of the Akt pathways.

Objective : To explore the role of Argonaute ( Ago) gene and RNA⁃Dependent RNA Polymerase (RDRP) gene of Aspergillus flavus in the growth and development about the RNAi mechanism . Methods : A. flavus Ago1 , Ago2 , RDRP1 , RDRP3 gene mutant strains were constructed by homologous recombination . The growth and development of the mutant strains were observed on potato dextrose agar(PDA) + uracil uridine (UU) medium inoculated with 3 μl 106 CFU/mL spores . 200 , 400 μg cell wall pressure agent conidored ( CR) , 0. 8 mol/L , 1 . 6 mol/L osmotic pressure agent NaCl , 2 mmol/L , 4 mmol/L oxidative pressure agent hydrogen peroxide (H2 O2 ) and 0. 01% , 0. 02% genomic damage agent methyl mesylate (MMS) were added to the Yeast extract Glucose Minimum (YGM) + UU medium to analyze the stress response of the mutant strains . Results : A. flavus mutant strains about ΔAgo1 , ΔAgo2 , ΔRDRP1 , ΔRDRP3 were successfully constructed and its growth and development were normal . The ΔAgo1 and ΔAgo2 strains reduced the stress effects on cell wall and osmotic pressure compared to the control . Ago1 gene deletion reduced the effect of H2 O2 , and conversely RDRP3 gene deletion increased the inhibition of H2 O2 . The Ago2 and RDRP1 strains reduced the effect on genetic damage agent . In addition , ΔRDRP1 increased the effect of osmotic stress . Conclusion The Ago1 , Ago2 , RDRP1 and RDRP3 genes of A. flavus are not in⁃ volved in the regulation of growth rate and asexual reproduction and can participate in the regulating of the host stress response to the environment .

【Objective】 To explore the protective effects of exogenous hydrogen sulfide （H2S） on oxygen glucose deprivation and re-oxygenation （OGD/R）-induced SH-SY5Y cell injury. 【Methods】 OGD/R model was established in SH-SY5Y cells. Based on interferences， SH-SY5Y cells were divided into control group （no interference）， OGD/R model group， and treatment groups （OGD/R model treated with different concentrations of NaHS （H2S donor）. The cells were cultured in low glucose medium without fetal bovine serum under 37 ℃， 93% N2 and hypoxia （2% O2） for 12 h， then in complete medium under normoxia （5% O2 ） for 24 h. CCK-8 was used to detect cell viability， and flow cytometry was used for assaying the level of cellular apoptosis. Western blot was used to detect the expression levels of endoplasmic reticulum stress-related proteins including glucose regulatory protein 78 （GRP78）， CCAAT/enhancer-binding homologous protein （CHOP）， NF-κB P65 and COX-2. 【Results】 The cell viability was lower in OGD/R model group than in the control group （P<0.05）. NaHS treatment at a concentration of 0-0.5 mmol/L increased cell viability in OGD/R model group in a dose-dependent manner （P<0.05）. In contrast， NaHS （C>0.5 mmol/L） decreased cell viability of OGD/R （P<0.05）. The apoptosis level of early stage in OGD/R model group was significantly higher than that in control group （P<0.05）. NaHS treatment at concentrations of 0.2 and 0.4 mmol/L lowered the apoptosis level of early stage in OGD/R model group （P<0.05）. Western blot showed that the protein expression levels of GRP78， CHOP， NF-κB p65， and COX-2 were significantly higher in OGD/R model group than those in control group （P<0.05）. When compared with OGD/R model group， the expression levels of GRP78， CHOP， NF-κBp65 and COX-2 were decreased by NaHS at concentrations of 0.2， 0.4 and 4 mmol/L （P<0.05）， but there was no statistically significant difference among the treatment groups （P>0.05）. 【Conclusion】 NaHS can rescue cell viability of OGD/R-induced cell injury. It may be achieved by inhibiting the activation of NF-κBp65 and COX-2 proteins induced by endoplasmic reticulum stress to reduce the level of cell apoptosis.

Objective:To explore the DNA methylation patterns and methylation differential genes of patients with coal-burning-borne endemic fluorosis, and to provide a basis for study of the pathogenesis of fluoride-induced body injury.Methods:A case-control study was conducted in Shuicheng County, Liupanshui, Guizhou Province, ten patients with severe fluorosis were selected as the fluorosis group in Douqing Township, where people burning high fluorine coal in open range all year round; and ten people without fluorosis phenotype were selected as the control group in Huaga Township, where firewood was the main fuel. Peripheral blood samples were collected from the two groups of people. Reduced representation bisulfite sequencing (RRBS) technique was used to detect the whole genome DNA methylation pattern ( n = 4) and DNA differentially methylated region (DMR), the DMR differential degree (log 2Ratio) and KEGG pathway enrichment analysis were used to screen the methylation differential genes, and real-time PCR was used to verify the mRNA expression levels of the candidate methylation differential genes( n = 10). Results:The methylation pattern analysis results showed that the methylation levels of all C bases in the genome DNA of the fluorosis group and the control group were (61.53 ± 0.59)% and (62.48 ± 1.53)%, respectively; among them, the methylated levels at CG sites were (63.75 ± 0.65)%, (64.36 ± 1.01)%, at CHG sites were (13.79 ± 0.72)%, (16.69 ± 4.06)%, and at CHH sites were (25.12 ± 1.72)%, (29.77 ± 3.97)%. Compared with the control group, patients in the fluorosis group had 1 000 DMR distributed on different autosomes; and the chromosome 19 was the most with 104 segments. There were 978 DMR-related genes, including 265 hypermethylation genes and 713 hypomethylation genes; KEGG pathway enrichment analysis showed that methylation differential genes were mainly involved in cell metabolism, cancers, and phosphatidylinositol 3-kinase-protein kinase B (PI3K-AKT) and other signaling pathways; combined with the differential degree of DMR, the hypermethylated succinate dehydrogenase complex flavoprotein subunit A pseudogene 3 (SDHAP3, log 2Ratio = 3.487) and hypomethylated nuclear factor κB inhibitor kinase regulatory subunit γ (IKBKG, log 2Ratio =-4.436) were selected as the candidate genes. There were statistically significant differences in the mRNA expression levels of SDHAP3 (0.54 ± 0.08, 1.00 ± 0.00) and IKBKG (1.32 ± 0.39, 1.00 ± 0.00) between fluorosis group and control group ( F = 22.94, 15.09, P < 0.01 or < 0.05). Conclusion:There are a large number of methylation differential genes in the genomes of patients with coal-burning-borne endemic fluorosis and controls, the hypermethylated SDHAP3 and hypomethylated IKBKG may be involved in fluoride induced body injury.

To construct TeI3c/4c-based and temperature-inducible gene inactivation system (Thermotargetron) and to apply it to gene inactivation of mesophilic bacteria. The subunit of flagellum (fliC) and C4 dicarboxylate orotate:H⁺ symporter (dctA) genes were chosen as targets in the genome of Escherichia coli HMS174 (DE3) strain. According to recognition roles of TeI3c/4c intron, the fliC489a, fliC828s, fliC1038s and dctA2a sites were chosen as target sites. Gene-targeting plasmids were constructed based on pHK-TT1A by using overlap PCR method and transformed into HMS174 cells. An aliquot mid-log phase cultures of the transformants were shocked at 48 °C and plated on LB plate (containing chloramphenicol). Afterwards, gene mutants were screened by using colony PCR and DNA sequencing. After the mutants were obtained, the phenotypes of ΔfliC and ΔdctA gene mutants were characterized by using agar puncture and carbon metabolism experiments. Colony PCR and sequencing results show that TeI3c/4c intron was inserted in the designed sites of fliC and dctA genes. The gene-targeting efficiency of Thermotargetron system was 100%. Phenotype verification experiments of the mutants demonstrated that the cell motility of all ΔfliC mutants was damaged and the malate assimilation ability of ΔdctA mutant was deprived comparing to wild-type HMS174 strain. In our study, a temperature-inducible and high-efficiency gene inactivation system was established for mesophilic bacteria. This system could achieve high efficiency and precise gene inactivation by modulation of the incubation duration of the transformants at 48 °C.

Objective:To investigate the clinical application of carbon nanoparticles mapping lymph nodes in curative resection for colorectal carcinoma.Methods:Patients diagnosed with colorectal cancer before operation and undergoing radical surgery with intact postoperative pathological data in the Sixth Affiliated Hospital, Sun Yat-sen University from March 2016 to March 2018 were included in this retrospective case-control study. Those who were diagnosed with ileus, recurrent carcinoma or underwent emergency operation were excluded. A total of 1421 cases were included, with 156 cases in the carbon nanoparticles mapping group and 1265 cases in the control group. Using 1∶3 case control matching based on gender, weight, TNM staging and neoadjuvant chemotherapy, 145 and 435 cases were finally recruited in the carbon nanoparticles mapping group and control group, respectively. Patients in the carbon nanoparticles mapping group underwent preoperative colonoscopy with carbon nanoparticles submucosal injection 2.4 (1.0 - 14.0) days before operation. Carbon nanoparticles of 0.25 ml was injected at 4 points (3, 6, 9 and 12 o'clock each) 0.5-1.0 cm around the tumor. The number of eliminated lymph node, number of positive lymph node and positive rate between the two groups were compared, and the number of eliminated lymph node in different subgroups of T stage, N stage, TNM stage and neoadjuvant chemotherapy was analyzed and compared.Results:After case control matching, total number of eliminated lymph nodes in the carbon nanoparticles mapping group was significantly higher than that in the control group (22.2±11.2 vs. 19.0±9.5, t=3.025, P=0.003). However, no statistically significant differences were found in the number of positive lymph node and lymph node positive rate between two groups (all P>0.05). Subgroup analysis showed that as compared to the control group, total number of eliminated lymph nodes in the carbon nanoparticles mapping group was significantly higher in T3 stage subgroup (median: 22 vs. 18, Z=2.435, P=0.015), N0 stage subgroup (median: 20.5 vs. 17.5, Z=2.772, P=0.006), TNM II stage subgroup (median: 23.5 vs. 19.0, Z=2.654, P=0.008) and neoadjuvant chemotherapy (median: 22.5 vs. 13.0, Z=3.287, P=0.001), while compared to the control group, the number of positive lymph node (median: 4.0 vs. 6.5, Z=-2.530, P=0.011) and the lymph node metastasis degree (median: 16% vs. 31%, Z=-2.862, P=0.004) were lower in the carbon nanoparticles mapping group in N2 subgroup. Conclusion:Carbon nanoparticles mapping lymph nodes can effectively enhance the number of eliminated lymph nodes in curative resection for colorectal cancer.