Objective To investigate the differences of protein and mRNA expression of matrix metalloproteinase 9 (MMP-9) in osteoclasts (OC) and osteoclast-like cells (OLC) obtained by mechanical and inducement methods. Methods Mechanical separation method was used to separate mature osteoclasts from long bones of SD rats aged one-day;and inducement culture method was applied to induce OLC by using RANKL (100 ng/mL) and M-CSF (100 ng/mL) . The protein expression of MMP-9 was measured by immunocytochemistry and mRNA expression of MMP-9 was assayed by in situ hybridization. Results The integral optical density (IOD) and average optical density (AOD) of positive cells in the visual field were higher in the 12-d group of inducement method as compared with the 3 d-group of mechanical method. Conclusions It is suggested that the protein and mRNA expression of MMP-9 in OLC obtained by 12 d inducement method is much high than in OC obtained by 3 d mechanical method. OLC obtained by inducement method can be applied in the study of osteoporosis.

OBJECTIVE To analyze the influential factors of cardioto xicity in patients with positive breast cancer of human epidermal growth factor receptor 2（HER-2）treated by trastuzumab combined with chemotherapy. METHODS From April 2017 to January 2021，200 HER-2 positive breast cancer patients receiving pirarubicin + cyclophosphamide combined with sequential paclitaxel+trastuzumab were collected from our hospital. According to the presence or absence of cardiotoxicity ，the patients were divided into cardiotoxicity group and non-cardiotoxicity group. The clinical data and echocardiographic results of the patients were collected，and the influential factors of cardiotoxicity were analyzed. RESULTS Among 200 patients，43 patients suffered from cardiotoxicity with the incidence of 21.5％. The proportion of patients with cardiotoxicity during pirarubicin+cyclophosphamide therapy accounted for 5.5％（11/200），and the proportion of patients with cardiotoxicity during sequential paclitaxel+trastuzumab therapy accounted for 20.5％（41/200）；the latter was significantly higher than the former （P＜0.01）. At the same time ，the decrease of left ventricular ejection fraction during sequential therapy of paclitaxel and trastuzumab was significantly higher than that during pirarubicin+cyclophosphamide therapy [ 14％（12％，17％）vs. 7％（3％，10％），P＜0.001]. Compared with patients without cardiotoxicity ，the proportion of patients with cardiotoxicity with a history of hyperlipidemia was significantly higher （P＜ 0.01），while the proportion of patients receiving dexrazoxane was significantly lower （P＜0.01）. Results of binary Logistic regression analysis showed that the history of hyperlipidemia [OR ＝3.672，95％ CI（1.499，8.992），P＝0.004] and the use of dextrazoxane [OR ＝0.154，95％ CI（0.072，0.330）， P＜0.001] were associated with the occurrence of cardiotoxicity. CONCLUSIONS Hyperlipidemia is an independent risk factor for cardiotoxicity induced by pirarubicin + cyclophosphamide combined with sequential paclitaxel+trastuzumab in HER 2 positive breast cancer patients ，while the use of dextrazoxane is a protective factor.