Objective To evaluate the role of c-Jun N-terminal kinase (JNK) and p38 mitogen-activated protein kinase (p38MAPK) signaling pathways in reduction of ischemia-reperfusion (I/R) injury by morphine preconditioning in the rats with heart failure.Methods Adult male Sprague-Dawley rats,weighing 200-230 g,in which doxorubicin 2 mg/kg was injected via the tail vein once a week for 6 consecutive weeks to induce chronic heart failure,were studied.At the end of 8th week,45 rats with chronic heart failure were randomly divided into 5 groups (n =9 each) using a random number table:sham operation group (group S),group I/R,morphine preconditioning group (group MPC),SP600125 (JNK inhibitor) + morphine preconditioning group (group MSP) and SB203580 (p38MAPK inhibitor) + morphine preconditioning group (group MSB).Myocardial I/R was induced by 30 min occlusion of the anterior descending branch of the coronary artery followed by 120 min reperfusion in each group except group S.In group MPC,the rats were subjected to 3 cycles of 5-min infusion of 0.1 mg/kg morphine via the femoral vein at 5 min interval before ischemia.In MSP and MSB groups,SP600125 0.5 mg/kg and SB203580 0.2 mg/kg were injected via the femoral vein,respectively,at 10 min before morphine preconditioning.The animals were sacrificed at 120 min of reperfusion,and the myocardial specimens were obtained for determination of the total areas of right and left ventricles (LV+RV),area at risk (AAR),infarct size (IS),and expression of PKC δ in myocardial tissues (by immunohistochemistry),and IS/AAR ratio was calculated.Results There was no significant difference in LV+RV and AAR between the five groups (P＞0.05).Compared with group S,IS and IS/AAR were significantly increased,and the expression of PKC δ was upregulated in I/R and MSB groups (P＜0.05).Compared with group I/R,IS and IS/AAR were significantly decreased,and the expression of PKC δ was down-regulated in MPC and MSP groups (P＜0.05).Compared with group MPC,IS and IS/AAR were significantly increased,and the expression of PKC δ was upregulated in group MSB (P＜0.05),and no significant change was found in the parameters mentioned above in group MSP (P＞0.05).Conclusion Activation of p38MAPK signaling pathway is involved in reduction of myocardial I/R injury by morphine preconditioning,and the mechanism is related to down-regulation of PKC δ expression in rats with heart failure;JNK signaling pathway is not involved in this process.

In order to ascertain prevalence rate of premarital sexual intercourse, unintended pregnancy and abortion, and evaluate associated factors of unintended pregnancy among undergraduates from all over China, the representative sample of unmarried undergraduates was obtained by using a multi-stage, stratified, probability cluster design, and data were collected by using a survey questionnaire. 62 326 available responders were gained. 11.6% of them acknowledged having experiences of premarital sexual intercourse (standardized prevalence rate of sexual intercourse was 13.8%). 31.5% of students active in premarital sex acknowledged undergoing unintended pregnancy. 76.2% of pregnant students selected abortion to end it. Of students active in premarital sex, 46.2% used contraception at the first sexual intercourse, 28.2% replied "always" using contraception in sexual intercourse. The rate of using condoms, oral contraceptives (OCs), and withdrawal among students who had used contraception was 52.0%, 31.0%, and 27.2% respectively. "No preparation for sex" (40.3%), "pleasure decrement" (32.1%), "won't-be-pregnancy in occasional sexual intercourse" (30.2%) were their common excuses for using no contraception. The identified risk factors for unintended pregnancy among students active in premarital sex by multivariate analysis were as follows: having no steady lover [having no steady lover vs having a steady lover: odds ratio (OR), 1.875; 95% confidence interval (CI), 1.629-2.158], unaware of the course of conception (unaware vs aware: OR, 2.023; 95% CI, 1.811-2.260), considering abortion not endanger women's physical and mental health (no endangerment vs endangerment: OR, 2.659; 95% CI, 2.265-3.121), nonuse of contraception (never use vs always use: OR, 1.682; 95% CI, 1.295-2.185). Medical students were not less likely to experience an unintended pregnancy than nonmedical students (OR, 1.111; 95% CI, 0.906-1.287). The substantial proportion of unintended pregnancy among undergraduates indicates a need for convenient and targeted contraceptive education and services.

Objective After hydrogen bonding between collagen ( COL) and silk fibroin ( SF ) at different concentrations, a composite scaffold with adjustable stiffness was prepared by combining with gel system, and its physical and chemical properties were characterized. Methods SF with different qualities was dissolved in sodium alginate (SA) solution, then COL solution at different concentration and calcium carbonate ( CaCO3 ) powder were added. The hydrogels of SC1, SC2, and SC3 groups were obtained by taking out the mixed solution and adding some gluconic acid lactone ( GDL) powder, and different SF scaffolds were obtained after freeze drying. Results The SF scaffolds with adjustable stiffness were successfully prepared. The compression moduli of SC1, SC2, and SC3 groups were (17. 31±2. 73), (24. 12±1. 81), (32. 54±1. 81) kPa, respectively. The innerstructure of the scaffolds was observed. From SC1 group to SC3 group, pores of the scaffolds were smaller and fewer, and hydrophilicity of the materials become better and better. Conclusions Three-dimensional ( 3D) porous scaffolds with different matrix stiffness can be prepared by changing the concentration of SF and COL solution. The concentration of SF and COL is proportional to the compression modulus, water absorption, water retention and swelling rate of SF scaffolds, while inversely proportional to porosity. The findings of this study are expected to provide theoretical guidance for construction of scaffolds with appropriate matrix stiffness for inducing osteogenic differentiation of mesenchymal stem cells

In order to ascertain prevalence rate of premarital sexual intercourse,unintended pregnancy and abortion,and evaluate associated factors of unintended pregnancy among undergraduates from all over China,the representative sample of unmarried undergraduates was obtained by using a multi-stage,stratified,probability cluster design,and data were collected by using a survey questionnaire.62 326available responders were gained.11.6％ of them acknowledged having experiences of premarital sexual intercourse (standardized prevalence rate of sexual intercourse was 13.8％).31.5％ of students active in premarital sex acknowledged undergoing unintended pregnancy.76.2％ of pregnant students selected abortion to end it.Of students active in premarital sex,46.2％ used contraception at the first sexual intercourse,28.2％ replied “always” using contraception in sexual intercourse.The rate of using condoms,oral contraceptives (OCs),and withdrawal among students who had used contraception was 52.0％,31.0％,and 27.2％ respectively.“No preparation for sex” (40.3％),“pleasure decrement” (32.1％),“won't-be-pregnancy in occasional sexual intercourse” (30.2％) were their common excuses for using no contraception.The identified risk factors for unintended pregnancy among students active in premarital sex by multivariate analysis were as follows:having no steady lover [having no steady lover vs having a steady lover:odds ratio (OR),1.875; 95％ confidence interval (CI),1.629-2.158],unaware of the course of conception (unaware vs aware:OR,2.023; 95％ CI,1.811-2.260),considering abortion not endanger women's physical and mental health (no endangerment vs endangerment:OR,2.659; 95％ CI,2.265-3.121),nonuse of contraception (never use vs always use:OR,1.682; 95％ CI,1.295-2.185).Medical students were not less likely to experience an unintended pregnancy than nonmedical students (OR,1.111; 95％ CI,0.906-1.287).The substantial proportion of unintended pregnancy among undergraduates indicates a need for convenient and targeted contraceptive education and services.