Objective To investigate the genotype and production of toxin A and B of C .difficile clinical isolates collected from Sydney ,Australia .Methods Sixty‐eight C .difficile clinical isolates were collected from Westmead Hospital ,the University of Sydney ,which were genotyped by using PCR‐ribotyping ,and toxin A ,B coding gene tcdA ,tcdB were detected by using PCR meth‐od .Results Thirty‐one PCR‐ribotypes (RTs) were confirmed in the 68 C .difficile clinical isolates ,RT014 (19 .1% ) and RT002 (11 .8% ) were the common genotypes .Sixty‐four of 68 (94 .1% ) isolates contained tcdA and tcdB for toxin A and B .Conclusion The common prevalent PCR‐ribotypes of C .difficile were RT014 and RT002 in Sydney ,most of the C .difficile clinical isolates contained toxin A and B .

Objective To investigate the genotype and variance of toxin associated genes of moxifloxacin‐resistant Clostridium difficile clinical isolates in Sydney .Methods Twenty‐two moxifloxacin‐resistant Clostridium difficile clinical isolates were collected from Sydney ,which were genotyped by using sequencer capillary gel electrophoresis based PCR‐ribotyping ,and toxin A and B cod‐ing gene tcdA and tcdB ,and binary toxin coding gene cdtA and cdtB were detected by using PCR method .Toxin regulator gene tc‐dC was analyzed by using PCR‐sequencing ,and was aligned with reference sequence of VPI 10463 (Genbank accession number :X92982) ,and the tcdC sequence types of all 22 isolates were identified by using blast tool in NCBI .Results Twenty‐one isolates were genotyped as hypervirulent PCR‐ribotypes 027 (RT027) ,and one isolate as RT078 ;all 22 isolates contained tcdA and tcdB for toxin A and B and cdtA and cdtB for binary toxin (tcdA+ tcdB+ cdtA+ cdtB+ ) .The tcdC sequence types of the 21 RT027 i‐solates belong to sc1 ,and that of the one RT078 isolate belongs to WA39 .Compared with tcdC reference sequence of VPI 10463 ,a consecutive 18 bp deletion (nt341 to 379) and one nucleotide deletion at position 117 were found in the 21 RT027 isolates ,and a consecutive 39 bp deletion (nt330 to 368) and one nucleotide mutation at position 184(C> T) were found in the one RT078 isolate . Conclusion Clostridium difficile hypervirulent RT027 was the common moxifloxacin resistant genotype ;Clostridium difficile hy‐pervirulent RT027 and RT078 clinical isolates contained genes for toxin A and B and binary toxin ,and contained gene sequence mu‐tation in toxin regulator gene tcdC .

Objective To investigate the carrying status and characteristics of Clostridium difficile isolated from infants.Methods Two hundred and thirty-eight stool specimens were collected from infant younger than 1 year old,that were hospitalized or outpatient from August to November 2015.Immunochromatography targeted GDH and toxin A&B of C.difficile was used for C.difficile screening,and those positive specimens were inoculated in CDIF and anaerobic culture.C.difficile isolates were genotyped by using slpA sequence typing (slpA ST),and tcdA,tcdB,cdtA and cdtB of C.difficile isolates were detected by PCR.Results Fifty C.difficile strains were isolated from 238 stool samples,and the isolated rates of C.difficile from <3 months,3 months to <6 months,and 6 months to 1 years old groups were 9.3%,17.6% and 27.3%(χ2=6.940,P=0.031<0.05),respectively.52.0%(26/50) of the C.difficile isolates were toxigenic,and 69.2% (18/26) toxigenic isolates harbored tcdA+tcdB+cdtA-cdtB-.Fifty C.difficile isolates were genotyped as 11 slpA STs,slpA ST fr-02 and kr-02 were the commonest genotypes in toxigenic C.difficile isolates;however,that was slpA ST xr-03 in non-toxigenic isolates.Conclusion High C.difficile carriage is found in infants younger than 1 year old,and more than half of C.difficile isolates are toxigenic.Most of toxigenic isolates harbored toxin A and B.The genotype of C.difficile isolates is different between toxigenic isolates and non-toxigenic isolates.

Objective To observe imaging manifestations of postparaplegic myositis ossificans(PPMO).Methods A total of 14 patients with clinically diagnosed PPMO who underwent X-ray examination of the lesion sites were retrospectively collected,among them 9 cases underwent CT and 4 cases underwent MR examination.Imaging manifestations of PPMO lesions were analyzed and staged.Results Among 14 cases,PPMO lesions located in soft tissue around bilateral hip joint in 8 cases,in soft tissue around unilateral hip joint in 3 cases,in bilateral thigh in 2 cases and in bilateral calf in 1 case.Early stage PPMO was assessed in 4 cases,while middle stage in 3 and late stage PPMO in 7 cases.X-ray films showed early stage PPMO represented as swelled soft tissue,with cloud flocculent high density ossification shadows and blurred edges in 4 cases.In 3 cases of middle stage PPMO,X-ray films showed patchy,strip-like high density ossification shadow with uneven density and clear edges.Lesions in 7 cases of late stage PPMO presented as large flake,banded high-density ossification shadow consistent to the long axis of backbone and muscle with clear edges on X-ray films.One case of early stage PPMO was characterized by swelled soft tissue and high density ossification shadow on CT,while 2 cases of middle stage PPMO showed patchy high-density ossification shadow with uneven density and local eggshell-like changes,and the typical lesions had concentric circle appearance with clear edges.Six cases of late stage PPMO showed large lamellar,cord-like high-density ossification lesions with uneven and low internal densities,myeloid cavity changes and increased marginal density presented as cortical-like changes on CT.On MRI,1 case of early stage PPMO was characterized by swelled soft tissue with long T1 and long T2 signals,blurred edges and feathery changes.One case of middle stage PPMO showed equal or slightly low signal on T1WI,uneven high signal on T2WI,and the signal intensities were higher than the surrounding muscle with stratifications,while the surrounding soft tissue and adjacent bone marrow showed low T1WI and high T2WI edema signals.Two cases of late stage PPMO showed equal and low signals on T1WI,uneven high signals on T2WI,cortical changes presented as low signals on the margin,and edema signals were found in the surrounding soft tissue.Conclusion Imaging manifestations of PPMO had certain characteristics.

Ferroptosis is a new form of regulated cell death discovered in recent years, which is iron-dependent cell death characterized by peroxidation of polyunsaturated fatty acid phospholipids. Recent studies have shown that radiotherapy can induce ferroptosis in cancer cells via ionizing radiation. Targeting ferroptosis plays a synergistic role in tumor suppression with radiation, which not only further deepens the connotation of radiobiology, but also provides a new perspective for tumor radiosensitization. This review systematically summarizes the occurrence and defense of ferroptosis, focusing on the key role of ferroptosis in the radiobiological effects of tumor cells and the potential application of ferroptosis in radiosensitization.

Objective:To screen and verify the key radioresistance genes regulated by m6A methylation in nasopharyngeal carcinoma (NPC) based on the chip data and cell experiments.Methods:The microarray data of NPC radioresistance genes, m6A regulated genes and mRNA expression profiles of NPC genes were downloaded from Gene Expression Omnibus (GEO) database. The differential genes were screened and statistically analyzed by R software. The biological processes, signal pathways and interaction networks of these genes were analyzed by bioinformatics. The m6A regulatory factors were knocked down and the radioresistant strains were constructed. The above m6A differential radioresistant genes of NPC were screened and verified by real-time reverse transcription PCR (qRT-PCR) and Western blot. The m6A modification of screened genes and their direct binding ability with methyltransferase 3 (METTL3) were verified by methylated RNA immunoprecipitation qPCR (MeRIP-qPCR). The siRNA of selected genes was transfected into NPC cells, and after treatment with ionizing radiation, cell proliferation was detected by CCK-8 assay and EdU, apoptosis and cell cycle were detected by flow cytometry, and radiosensitivity was detected by clone formation assay. The trend of differences in the abundance of Fe 2+ and lipid peroxidation between the control and EGLN3 knockdown groups after ionizing radiation treatment was compared by paired t-test. Results:Chip data GSE48501 intersected with GSE200792 and GSE53819 to obtain 6 differential genes, including EGLN3, FOSL2, ADM, JUN, VEGFA and PRDM1. The target genes of EGLN3 and FOSL2 were further screened by TNMplot and KMplot, etc. The mRNA of the target genes directly bound to METTL3 and were subjected to its mediated modification of m6A. The target genes were up-regulated in the parental cells after irradiation in a dose and time gradient manner, which were also significantly up-regulated in radioresistant cells. After EGLN3 and FOSL2 were down regulated, the proliferation activity of NPC cells was more significantly decreased after irradiation, and the radiosensitization ratio was statistically significant compared with that of NPC cells without EGLN3 and FOSL2 down-regulation. After irradiation, EGLN3 down-regulated NPC cells significantly down-regulated glutathione peroxidase 4 (GPX4) expression, increased the abundance of Fe 2+ and lipid peroxidation, which played a role in radiosensitization by inducing ferroptosis. Conclusions:EGLN3 and FOSL2 play a role in radioresistance in NPC through METTL3 mediated m6A methylation. Down-regulation of EGLN3 combined with ionizing radiation can increase the intracellular Fe 2+ abundance and lipid peroxidation and down-reuglate the expression of GPX4 in NPC cells, which can enhance radiosensitization for NPC radiotherapy by the ferroptosis pathway.

Objective To investigate the regulation and mechanism of microRNA (miR)-98-5p on cisplatin sensitivity in cisplatin-resistant cervical cancer cells. Methods The cisplatin(DDP) +miR-NC group (transfected miR- NC), DDP + miR-98-5p group (transfected miR-98-5p mimics), DDP + si-NC group (transfected si-NC), DDP + si- ribonucleotide reductase subunit M2 (RRM2) group (transfected si-RRM2), DDP + miR-98-5p + pcDNA group (co- transfected miR-98-5p mimics and pcDNA), DDP + miR-98-5p + pcDNA-RRM2 group (co-transfected miR-98-5p mimics and pcDNA-RRM2) were transfected into HeLa/DDP cells by liposome method. Real-tim PCR, Western blotting, CCK-8, Transwell chamber and dual luciferase reports gene detection assay were used to detect the expression of miR-98-5p, RRM2, cyclin Dl, P21, matrix metalloproteinase (MMP)-2 and MMP-9 in cells, inhibition rate, half inhibitory concentration(IC