Expression of Slit and Robo during remodeling of corticospinal tract in cervical spinal cord in middle cerebral artery occlusion rats.

BACKGROUND: Slits and Robos were associated with the generation of axons of corticospinal tract during the corticospinal tract (CST) remodeling after the cerebral ischemic stroke (CIS). However, little is known about the mechanism of CST remodeling. In this study, we detected the expression of Slits and Robos in middle cerebral artery occlusion (MCAO) rats to investigate the roles of Slits and Robos in the CIS. METHODS: MCAO model was established using modified Zea Longa method. Beam walking test (BWT) was conducted to evaluate the motor function. The images of the track of cortical spinal cord beam on day 7, 14 and 21 were observed by anterograde CST tracing. Biopinylated dextan amine (BDA) was used to mark CST anterogradely. Expression of GAP-43 mRNA and GAP-43 protein in cervical spinal cord was detected by Real-Time PCR and Western blot analysis, respectively. The expression of Slit1, Slit2 and Robo1 in cervical spinal cord was detected by immunofluorescence staining. RESULTS: The scores in the model group were significantly reduced compared to sham-operation group on day 7 (P < 0.001), 14 (P < 0.001) and 21 (P < 0.001), respectively. There was no significant difference in the score on day 7, 14 and 21 of the sham-operation groups (P > 0.05). In contrast, significant increase was noticed in the scores in model group, presenting a time-dependent manner. More CST staining fibers could be observed at the degenerative side in the model group compared with that of the sham-operation group on day 21. GAP-43 mRNA expression in the model group showed significant increase compared to that of sham-operation group on day 14 (P = 0.015) and 21 days (P = 0.002). The expression of GAP-43 protein in model group showed significant increase compared to that of sham-operation group on day 14 (P = 0.022) and day 21 (P = 0.008), respectively. The expression of Slit1 and Slit2 showed increase on day 14 and day 21, while the expression of Robo1 showed significant decrease in MCAO rats. CONCLUSION: Up-regulation of Slit1 and Slit2 and the downregulation of Robo1 may be related to the axons of CST midline crossing in spinal cord of MCAO rat during the spontaneous recovery of impaired motor function.

[Dynamic analysis of drug resistance of Pseudomonas aeruginosa in laboratory and clinical two-drug regimen].

OBJECTIVE: To analyze drug resistance status of Pseudomonas aeruginosa in the two-drug regimens in laboratory and clinical settings for more appropriate application of antibiotics. METHODS: The laboratory data of drug resistance rate of Pseudomonas aeruginosa identified with Biomerieux Vitek 32 system were collected. The clinical two-drug regimen data corresponding to anti-microbial sensitivity test were investigated, and the resistance rate of the clinical two-drug regimen was analyzed statistically. RESULTS: The isolation rate of Pseudomonas aeruginosa with multi-drug resistance increased steadily in recent years, and the resistance rate to 6 widely used antibiotics increased by over 20%. Two Pseudomonas aeruginosa strains resistant to all the 6 drugs were identified in January 2004, and till June 2005, totally 18 panresistant strains had been isolated with dramatic increases in MIC value. In the clinical two-drug regimen, sulbactam/amikacin, sulbactam/ciprofloxacin, tazobactam/amikacin, and imipenem/amikacin still had low resistant rates. CONCLUSIONS: Multi-drug resistance of Pseudomonas aeruginosa to the antibiotics is a serious problem. A two-drug regimen based on anti-microbial susceptibility test should be chosen.