Objective:To establish an HPLC method for the determination of N,N'-diacetyl-L-cystine in com-pound amino acid injection.Methods:The HPLC method parameters were as follows,The Atlantis dC18 column(4.6 mm × 150 mm,3 μm),The mobile phase was aammonium formate solution(315 mg ammonium formate was taken and dissolved with 960 mL water)-acetonitrile-methanoic acid(970∶30∶1)as a mobile phase,at a flow rate of 0.7 mL·min-1,and the detection wavelength of 210 nm.Results:The linear range of N,N'-diacetyl-L-cystine was 2.697-53.94 μg·mL-1(r=0.999 9),the limits of detection and quantification were 1.4 μg·mL-1 and 4.4 μg·mL-1 respectively.The average recovery was 100.2％with RSD of 0.5％.Conclusion:The method was proved to be suitable for the determination of N,N'()-diacetyl-L-cystine in compound amino acid injection.

Objective To evaluate the effectiveness of tumor cell Vimentin combined with endoscopic ultrasound-guided fine-needle biopsy(EUS-FNB)in diagnosing solid pancreatic tumors.Methods Clinical data from 110 patients who underwent EUS-FNB from October 2021 to December 2023 were retrospectively analyzed.Solid pancreatic tumors including but not limited to pancreatic cancer and pancreatic neuroendocrine tumors.The sensitivity,specificity,and accuracy of EUS-FNB were assessed by comparing its results with the final pathological diagnoses.Result Clear histopathological diagnoses were obtained in 106 cases,accounting for 96.37%.Among them,87 cases were definitively diagnosed as adenocarcinoma or pancreatic ductal adenocarcinoma.Immunohistochemical staining showed that Vimentin was expressed in the tumor cells.There was no statistically significant difference in positive rates among biopsies from different anatomical sites(P>0.05),but significant differences were observed in lesions of different diameters(P<0.05).Immunohistochemical staining suggested that Vimentin expression levels might be associated with the nature of the lesions.The overall diagnostic accuracy,sensitivity,and specificity of Vimentin combined with EUS-FNB for pancreatic masses were 86.09%,84.57%,and 100.00%,respectively.Specifically,for solid masses,the diagnostic accuracy,sensitivity,and specificity were 87.67%,86.55%,and 100.00%,respectively.For pancreatic cystic tumors,the diagnostic accuracy,sensitivity,and specificity were 65.42%,69.79%,and 100.00%,respectively.Conclusion The combination of tumor cell Vimentin and EUS-FNB demonstrates high diagnostic accuracy for solid pancreatic tumors,making it a valuable tool for clinical application.