Résumé
Objective: To investigate the effect and mechanism of helix B surface peptide (HBSP) on myocardial ischemia reperfusion injury (MIRI) in experimental mice. Methods: The MIRI model was established by ligation of anterior descending coronary artery of the mice for 45 min and followed by corresponding treatment at 5 min before reperfusion. A total of 64 male ICR mice were randomly assigned to 4 group:①Sham group,②MIRI group, the mice received normal saline at 5 min before reperfusion,③HBSP group, MIRI mice received HBSP at 5 min before reperfusion and④HBSP+PD98059 group, MIRI mice received PD98059 (a speciifc blocker of ERK1/2) at 20 min before reperfusion and followed by HBSP at 5 min before reperfusion.n=16 in each group, all animals were treated for 2 hours. The area of myocardial infarction (MI) was detected by TTC-EB double staining method, the myocardial apoptosis rate was examined by TUNEL method, the levels of protein expression of ERK1/2 and phosphorylation of ERK1/2 were measured by Western blot analysis. Results: Compared with MIRI group, HBSP group presented decreased MI area, decreased myocardial apoptosis rate and increased phopsphorylation level of ERK1/2, allP Conclusion: HBSP may reduce the MI area via inhibiting myocardial apoptosis and therefore, protecting the experimental mice from MIRI; the mechanism might be related to the activation of ERK1/2 pathway.
Résumé
<p><b>OBJECTIVE</b>To explore the feasibility of inducing fungal infection by Cryptococcus neoformans aerosol inhalation in immunosuppressed Balb/c mice.</p><p><b>METHODS</b>Twenty-four Balb/c mice were randomized into cyclophosphamide (CTX) group and control group (n=12). The mice in CTX group were subject to inhalation of Cryptococcus neoformans aerosol prepared using a ultrasonic nebulizer 4 days after intraperitoneal CTX injection, and the control mice received the inhalation only. The leukocyte count and changes in appetite, body weight, and behaviors of the mice were observed after the treatments. On days 3 and 7 after the inoculation, the mice were sacrificed to analyze the fungal counts in brain and lung tissue homogenates and examine the pulmonary pathologies.</p><p><b>RESULTS</b>CTX injection caused lowered appetite and body weight loss in the mice, and significantly reduced the leukocyte counts (2.77∓0.45 vs 8.26∓0.56, P<0.05). At days 3 and 7 after inoculation, the Cryptococci load in the lungs increased obviously in CTX group with a colony-forming unit (CFU) of the lungs of 271.67∓122.22 and 41.67∓0.28, respectively, significantly higher than that in the control group (60.00∓43.36 and 3.00∓5.30, respectively, P<0.05). In CTX group, the CFU was 10.17∓5.42 and 9.17∓6.34 in the peripheral blood and 6.83∓4.92 and 11.00∓5.44 in the brain tissue at days 3 and 7, respectively, whereas no Cryptococci was detected in the peripheral blood or in the brain tissue in the control group. Pathological examination of the lungs revealed destruction of normal alveolar structure in CTX group, with numerous infiltrating inflammatory cells and visible yeast.</p><p><b>CONCLUSION</b>Inhalation of Cryptococcus neoformans aerosol can cause fungal infection in the lungs of immunosuppressed Balb/c mice.</p>