Objective:To evaluate the role of ubiquitin-specific peptidase 22 (USP22) in myocardial ischemia-reperfusion (I/R) injury in diabetic mice.Methods:Seventy-eight SPF male C57BL/6 mice, aged 6-8 weeks, were divided into 6 groups using a random number table method: sham operation group (Sham group, n=12), type 1 diabetes mellitus + sham operation group (T1D+ Sham group, n=12), myocardial I/R injury group (I/R group, n=12), type 1 diabetes mellitus + myocardial I/R injury group (DI/R group, n=12), type 1 diabetes mellitus + myocardial I/R injury + empty vector group (DI/R+ V group, n=15), and type 1 diabetes mellitus + myocardial I/R injury + USP22 overexpression group (DI/R+ U group, n=15). Type 1 diabetes mellitus was induced by intraperitoneal injection of streptozotocin-citrate buffer. Myocardial I/R was induced by ligation of the left coronary artery. At 1 day before developing the myocardial I/R injury model, DI/R+ U group and DI/R+ V group received an intramyocardial injection of USP22 overexpression plasmid or empty vector plasmid, respectively. At 24 h of reperfusion, cardiac function was assessed using the echocardiography to measure the left ventricular ejection fraction and left ventricular fractional shortening. The mice were then sacrificed, and their hearts were harvested for measurement of the myocardial infarct size, for microscopic examination of pathological changes (using HE staining) and for determination of the apoptosis rate (TUNEL staining), reactive oxygen species(ROS) activity (DHE staining), and USP22 expression (by Western blot, immunofluorescence, and immunohistochemistry). Proteomic analysis was performed to identify downstream proteins regulated by USP22, and protein-protein interactions were investigated using co-immunoprecipitation. Results:Compared with Sham group, the cardiac function indices were significantly decreased, the apoptosis rate of myocardial cells and ROS activity were increased, and USP22 expression in myocardial tissues was down-regulated in I/R group ( P<0.05). Compared with I/R group, the percentage of myocardial infarct size was significantly increased, the cardiac function indices were decreased, the apoptosis rate of myocardial cells and ROS activity were increased, and USP22 expression in myocardial tissues was up-regulated ( P<0.05), and the pathological damage to myocardial tissues was aggravated in DI/R group. Compared with DI/R+ V group, the percentage of myocardial infarct size was significantly decreased, the cardiac function indices were increased, the apoptosis rate of myocardial cells and ROS activity were decreased, and USP22 expression in myocardial tissues was up-regulated ( P<0.05), and the pathological damage to myocardial tissues was alleviated in DI/R+ U group. The results of proteomics combined with co-immunoprecipitation experiments showed an interaction between calponin 1 and USP22. Conclusions:During myocardial I/R injury in diabetic mice, USP22 may act as an endogenous protective mechanism, and calponin 1 might be a downstream mechanism through which USP22 exerts its protective effects.

Pneumococcal vaccine plays a key role in preventing diseases such as pneumonia and meningitis caused by Streptococcus pneumoniae(S.pneumoniae).Capsular polysaccharide,C-polysaccharide and phosphorus content are important indicators for quality control of polysaccharide antigens in vaccine development and production.In this study,a quantitative 1H NMR and 31P NMR method based on a single internal standard hexamethylphosphoramide(HMPA)was developed to achieve simultaneous determination of capsular polysaccharide,C-polysaccharide and phosphorus content in 6A,6B,18C,19A,19F and 23F S.pneumoniae polysaccharide antigens.Using the internal reference comparison method,the effect of solubility of polysaccharide on quantitative 1H NMR determination was investigated.It was found that the determination results of quantitative 1H NMR were affected by the viscosity and concentration of polysaccharide solution.It was found that high viscosity polysaccharides at 3-15 mg/mL and low viscosity polysaccharides at 5-25 mg/mL were the optimal detection solution concentration range.This"one internal standard three quantitative"NMR method has good precision,specificity and accuracy,and provides a valuable new strategy for the quality control of pneumococcal vaccine.

AIM: To investigate the absorption of helicid in different segments of intestine based on rat everted intestine sac model. METHODS: To establish a high-performance liquid chromatography method for simultaneous determination of helicid and its metabolite. Krebs-ringer solution containing helicid was added to everted intestine sacs of different segments (duodenum, Jejunum, ileum and colon). Drug concentration in sacs was determined at different time points (5, 10, 15, 30, 45, 60, 75, 90 min). Adsorptions of helicid in four intestinal segments were compared. RESULTS: This high-performance liquid chromatography was successfully applied to the simultaneous determination of helicid and its metabolite. Absorption of helicid was rapid and time-dependent. The absorption and metabolism of helicid in duodenum segment were higher than these in other segments. CONCLUSION: The duodenum segment is the main site of segmental absorption and metabolism of helicid. This is the first report on intestinal segment metabolism of helicid.