OBJECTIVE:To determine the contents of salicylic acid and the related substances in salicylic acid ointment by HPLC.METHODS:The determination was performed on Kromasil ODS-C18 chromatographic column with mobile phase consisted of methanol-water(adjust pH=2.5 using acetic acid,50∶50)at a flow rate of 1.0 mL?min-1.The sample size was 20 ?L and the detection wavelength was set at 270 nm.RESULTS:The main peak and the related substances were well-separated.The linear range of salicylic acid was 10.014～100.14 ?g?mL-1(r=0.999 9)with an average recovery of 99.35%(RSD=0.99%)and a lowest detectable limit of 5 ng?mL-1,the labeled amout of related substances all less than 1.01%.CONCLUSION:The method developed in our study is simple in operation,accurate in results,specific and suitable for the content determination of salicylic acid ointment.

Vertebral artery hypoplasia is a frequent variation type of vertebral arteries.At present,there is no unified theory about the relationship between vertebral artery hypoplasia and posterior circulation ischemic stroke.The available evidence suggests that vertebral artery hypoplasia may be a precipitating factor for posterior circulation ischemic stroke; particularly other vascular risk factors coexist.This article elaborates the epidemiology of vertebral artery hypoplasia,the clinical manifestation and imaging features of vertebral artery hypoplasia in patients with posterior circulation ischemic stroke,and the possible mechanism of vertebral artery hypoplasia caused posterior circulation ischemic stroke.

Objective To investigate the diagnostic values of transcranial Doppler ultrasonography (TCD) for vertebral artery hypoplasia (VAH) and focal vertebral artery stenosis (fVAS) with CT angiography (CTA) finding as a standard.Methods Consecutive patient who underwent TCD and CTA were included.According to the findings of CTA,they were divided into 3 groups:a normal group,a VAH group,and a fVAS group.The TCD parameters included the mean flow velocity (MFV),peak systolic velocity (PSV),pulsatility index (PI),resistance index (RI) and asymmetry index (AI),and they were compared among the groups,respectively.The receiver operator characteristic (ROC) curves were used to evaluate the sensitivity and specificity of TCD parameters for diagnosis of VAH and fVAS.Results A total of 405 patients were enrolled,including 278 (68.6％) in the normal group,75 (18.5％) in the VAH group,and 52 (12.8％) in the fVAS group.There were significant differences in MFV,PSV,PI,and RI on the affected sides among different groups (the affected side in the normal group was defined as the right side).The blood flow velocity in the VAH group was the slowest,and that in the fVAS group was the fastest.Other parameters had the same trend.There were significant differences in MFV and PSV on the unaffected side among different groups.The blood flow velocity in the VAH group was significantly faster,the fVAS group was slightly faster,and the fVAS group was less than the VAH group.There were significant differences in AI among different groups,and it could be used as an indicator for diagnosis of VAH (the area under the curve 0.78,95％ confidence interval 0.72-0.84;P＜0.001).With the AI ＞33.7％ as a cut-off value,the sensitivity and specificity of VAH diagnosis were 74.7％ and 68.7％.Conclusions Attention should be paid to identifying VAH and fVAS when using TCD for evaluation of vertebral artery.AI ＞33.7％ can be used as a reference index for diagnosis of VAH.

Objective: To investigate the role of exosome (EXO) transporting Let-7a to regulate MYC gene in the malignant biological behaviors of triple negative breast cancer (TNBC) cell, and to explore the underlying mechanism. Methods: After the completion of cell culture, the gene and protein expressions of MYC and Let-7a in TNBC MDA-MB-231cells were detected by qPCR and WB, respectively. Recombinant lenti-virus vector carrying Let-7a and Crisper/Cas-9 system with MYC knockdown were transfected into MDA-MB-231 cells; MTT assay, Transwell assay and Scratch healing assay were performed to examine the proliferation, invasion and migration of MDA-MB-231 cells. Luciferase activity assay was performed to validate the binding between MYC and Let-7a. EXO was isolated and identified by transmission electron microscopy and WB assay in wild-type and Let-7a over-expressed MDA-MB-231 cells, respectively. After co-incubation of two types of EXO and MDA-MB-231 cells, the effects of Let-7a on biological behaviors of MDAMB-231 cells via EXO were detected by qPCR, WB, MTT and Transwell etc. Results: Let-7a was negatively correlated with MYC in breast cancer tissues and cell lines (all P<0.05); MYC promoted while Let-7a inhibited the proliferation, migration and invasion of breast cancer cells (all P<0.01); Let-7a silenced MYC by acting on 3'UTR of MYC gene, thereby reducing the expression of MYC protein (P<0.05); Let-7a was enveloped by EXO and transported to cancer cells, there by inhibiting the proliferation, migration and invasion of MDA-MB-231 cells. Conclusion: EXO some mediated Let-7a silences MYC gene by acting on its 3'UTR region, thus inhibiting the proliferation, migration and invasion of MDA-MB-231 cells.