The amino-terminal pro-C-type natriuretic peptide(NT-proCNP)is a diagnostic inflam-matory marker clinically used for diagnosing bacterial infections.This study aims to establish a phage display library of single-chain variable fragment(scFv)antibodies against canine NT-proC-NP and to screen for scFvs with high binding affinity to NT-proCNP.Initially,NT-proCNP was prepared using prokaryotic expression system and was used to immunize New Zealand White rab-bits.Upon achieving the desired serum titer,total RNA was extracted from the splenocytes of rab-bits and reverse transcribed into cDNA.Using this cDNA as a template,degenerate primers were employed to amplify the genes of the rabbit antibody light chain variable region(VL)and heavy chain variable region(VH).The VL and VH regions were spliced together to form a complete scFv fragment via overlap extension PCR.The scFv was then ligated into the phagemid pComb3XSS and electroporated into competent E.coli TG1 cells to construct a rabbit-derived anti-NT-proCNP scFv immunological library.This library underwent four rounds of enrichment and screening to isolate specific single-chain antibodies.The selected antibody was subsequently ex-pressed in a soluble form within a prokaryotic system,and its immunological activity was evalua-ted.Using phage display technology,this study successfully identified a single-chain antibody scFv-1-CNP with strong antigen-binding activity and genetic sequence characteristics of scFvs,providing a research direction for further exploration of scFv applications in the detection of NT-proCNP.

The amino-terminal pro-C-type natriuretic peptide(NT-proCNP)is a diagnostic inflam-matory marker clinically used for diagnosing bacterial infections.This study aims to establish a phage display library of single-chain variable fragment(scFv)antibodies against canine NT-proC-NP and to screen for scFvs with high binding affinity to NT-proCNP.Initially,NT-proCNP was prepared using prokaryotic expression system and was used to immunize New Zealand White rab-bits.Upon achieving the desired serum titer,total RNA was extracted from the splenocytes of rab-bits and reverse transcribed into cDNA.Using this cDNA as a template,degenerate primers were employed to amplify the genes of the rabbit antibody light chain variable region(VL)and heavy chain variable region(VH).The VL and VH regions were spliced together to form a complete scFv fragment via overlap extension PCR.The scFv was then ligated into the phagemid pComb3XSS and electroporated into competent E.coli TG1 cells to construct a rabbit-derived anti-NT-proCNP scFv immunological library.This library underwent four rounds of enrichment and screening to isolate specific single-chain antibodies.The selected antibody was subsequently ex-pressed in a soluble form within a prokaryotic system,and its immunological activity was evalua-ted.Using phage display technology,this study successfully identified a single-chain antibody scFv-1-CNP with strong antigen-binding activity and genetic sequence characteristics of scFvs,providing a research direction for further exploration of scFv applications in the detection of NT-proCNP.

Objective To explore the diagnostic value of multi-slice spiral CT combined with vimentin in dedifferentiated liposarcoma(DDL).Methods A total of 88 patients with suspected DDL admitted to No.904 Hospital of Joint Logistics Support Force of PLA from June 2017 to June 2022 were enrolled.Multi-slice spiral CT examination and vimentin detection were performed in all the patients.Pathological results were taken as the golden standard of diagnosis.The consistency of multi-slice spiral CT examination and pathological results was investigated.The expression of vimentin was compared between DDL patients and non-DDL patients.The diagnostic value of multi-slice spiral CT combined with vimentin in dedifferentiated liposarcoma was analyzed.Results Pathological diagnosis showed that 64 patients were diagnosed as DDL and 24 patients were not DDL.The results of multi-slice spiral CT showed that 63 patients were diagnosed as DDL.CT results of 59 patients with DDL and 20 patients with non-DDL were consistent with pathological diagnosis.The multi-slice spiral CT examination and pathological results were generally consistent(Kappa=0.746,P<0.01).The expression of vimentin was positive in 59 DDL patients and negative in 5 DDL patients.The expression of vimentin was positive in 6 non-DDL patients and negative in 18 non-DDL patients.Kappa consistency test showed that and the 2 diagnostic methods were generally consistent(Kappa=0.681,P<0.01).Sixty-three patients were diagnosed as DDL by multi-slice spiral CT combined with vimentin detection.The combined detection of 61 patients with DDL and 22 patients with non-DDL were consistent with pathological diagnosis.Kappa consistency test showed that,the 2 diagnostic methods were well consistent(Kappa=0.866,P<0.01).The sensitivities of multi-slice spiral CT,vimentin detection and their combination were 92.18% ,92.18% and 95.31% ,respectively;the specificities were 83.34% ,75.00% and 91.67% ,respectively;the Youden indexes were 0.755,0.671 and 0.870,respectively.The combined use of multi-slice spiral CT and vimentin detection had higher diagnostic value for DDL.Conclusion The result of multi-slice spiral CT combined with vimentin detection is consistent with pathological diagnosis and this method can be widely used in clinic.