Objective To investigate the long-term effects of xanthine oxidase inhibitor,oxypurinol on myocardial contractility of post-ischemic heart failure in mice,and explore the underlying mechanism. Methods One hundred and twenty SV120 mice were randomly assigned into myocardial infarction control group,sham operation group and Oxy treatment group.Post-ischemic heart failure were induced by left anterior descending coronary artery ligation in myocardial infarction control group and Oxy treatment group,and mice in Oxy treatment group and sham operation group were orally administered with 0.5 mmol/L Oxy each day.Nine to eleven months after treatment,echocardiography was performed in all groups.Trabeculae from the right ventricle of mice were dissected for assessment of changes in excitation-contraction coupling.Sarcomere length was measured by laser diffraction.Intracellular free Ca~(2+) concentration([Ca~(2+)]_I)was detected with fluorescent dye Fura-2,which was microinjected iontophoretically into cells. Steady-state force-[Ca~(2+)]_I was achieved by addition of ryanodine and increasing the stimulus frequency to induce tetanization,and the relationship between myocardial contractility and intracellular Ca~(2+) transients was analysed.Besides,Western blotting was performed to determine the oxidation of myofilament proteins. Results Long-term oral administration of oxypurinol significantly improved myocardial contraction function and reduced ventricular wall thickness.Programming of excitation-contraction coupling was significantly improved,and maximal Ca~(2+) activated force(F_(max))in steady-state wag also significantly increased.Western blotting revealed the oxidative modification of actin in mice of Oxy treatment group was significantly inhibited compared with that of myocardial infarction control group. Conclusion Long-term treatment with Oxy improves the cardiac contraction function and boosts the cardiac force dramatically in post-ischemia heart failure.The increase in contraction is the result of increased myofilament Ca~(2+) responsiveness.Thus,antioxidant oxypurinol,by preventing oxidative damage to contractile proteins,can augment contraction with little changes in[Ca~(2+)]_I,represents new class of inotropic agents with advantages of reducing Ca~(2+) overload,and offers new promises in management of heart failure in the future.

Objective:To investigate the immune effects of Clostridium difficile toxoid B (CdtB) vaccine formulated with different mucosal adjuvants through microneedle immunization, and to provide ideas for the prevention and treatment of Clostridium difficile infection. Methods:CdtB vaccine was prepared with purified Clostridium difficile toxin B(TcdB) after formaldehyde detoxification. Female BALB/c mice were immunized with different doses of vaccine alone or in combination with mucosal adjuvants. The titers of specific serum IgG and fecal IgA were detected at 0 d, 7 d, 14 d, 28 d and 42 d after immunization. The protective effects of CdtB vaccine were evaluated by cell neutralization assay and Clostridium difficile challenge infection. Results:(1) With the increase of immune dose, the mice immunized with CdtB vaccine alone by microneedle not only produced better serum specific IgG, but also had higher level of IgA in feces. (2) When the mice were immunized with CdtB vaccine containing LT or CTB adjuvant by microneedle, the trend of serum specific IgG titer in each group increased with the increase of immune dose, especially in the group containing LT adjuvant. There were significant differences in the trend of specific IgA titer in feces between the adjuvant groups and the group without adjuvant, but the adjuvant effect was not obvious. (3) No significant difference in serum IgG titer was observed between the mice immunized with 10 μg CdtB by microneedle or intraperitoneal injection, but microneedle immunization significantly increased fecal IgA level. (4) The neutralization titers of specific antibodies in mouse serum after immunization and the test results of challenge protection in mice confirmed that the use of CdtB vaccine had certain protective effects.Conclusions:CdtB vaccine had better immune effects in mice through microneedle immunization, but the adjuvant effects of LT and CTB were not significant.