RESUMO
Objective To observe the effects of melatonin (MT) on the expression of heme oxygenase-1 (HO-1),phosphorylated adenine dinucleotide quinone oxidoreductase-1 (NQO-1) and nuclear factor erythroid-2-related factor 2 (Nrf2),so as to explore the mechanism of MT's action in the Nrf2-ARE signaling pathway.Methods A total of 72 Sprague-Dawley rats were randomly divided into a control group,an injury group and a melatonin group,each of 24.T11-T12 acute SCI was induced in the injury and melatonin groups using the modified Allen's method.Ten minutes after the injury,equal amounts of absolute ethyl alcohol and melatonin were intraperitoneally injected into the rats in the injury and melatonin groups.For the control group,the vertebral plate was cut to expose the T11-T12 spinal cord without any injury of the nerves.Six rats from each group were randomly selected for sacrifice at 6,12 and 24 hours after the operation,and T11-T12 spinal cord specimens were collected.The spinal cord injury and inflammatory response were observed using haematoxylin eosin staining.The expression of HO-1,NQO-1 and Nrf2 was examined using immunofluorescence,while the expression of HO-1,NQO-1 and Nrf2 protein and mRNA were detected using RT-PCRs.Results The neuronal cells in the spinal cords of the control rats were of normal shape,without edema,necrosis or obvious hemorrhagic foci.Hemorrhagic foci,significantly more inflammatory cells and some spinal cord neurons with edema and necrosis were observed in the injury group.However,significantly fewer hemorrhagic spots and cells with edema were found in the melatonin group compared with the injury group.The average expression of HO-1,NQO-1 and Nrf2 protein and mRNA was significantly higher in the melatonin group than in the other two groups.The levels in the injury group were also significantly higher than in the control group 12 and 24 hours after the experiments.Immunofluorescence showed that the greatest number of cells with HO-1,NQO-1 and Nrf2 was found in the melatonin group,followed by the injury group and then the control group,with significant differences among all 3 groups.Conclusion Melatonin can promote the expression of HO-1,NQO-1 and Nrf2 in rats with acute spinal cord injury,which might be related with its activating the Nrf2-ARE signaling pathway.
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Objective To investigate the exfoliative toxin serotype genes and antibiotic resistance of Staphylococcus aureus (SA) isolated from children with staphylococcal scalded skin syndrome (SSSS). Methods In total, 108 strains of SA were isolated from 36 patients with SSSS, 36 patients with impetigo and 36 patients with abscess. Multiplex PCR was used to detect the staphylococcal exfoliative toxin A, B and D genes, Kirby-Baner method to test the susceptibilities of SA strains to 20 antibiotics. Results All the 36 SA isolates from SSSS patients were ET-positive, and 2 (6%) produced ETA, 7 (19%) ETB, 27 (75%) both ETA and ETB; of the 36 isolates from patients with impetigo, 78% produced ET, and 14% produced ETA, 64% produced both ETA and ETB, while no single ETB-producing strain was found; ET was detected in only one (2.8%) SA isolate from abscess patients, which produced both ETA and ETB. ETD was detected in none of the SA isolates. There was a statistical difference in the distribution of ET serotype among the three diseases (χ2=89.4, P < 0.01) and the proportion of ET-producing strains in SSSS group was signifi-cantly higher than that in impetigo group (χ2=9.0, P < 0.01) and abscess group (χ2= 68.1, P < 0.01). All the SA isolates were highly resistant to penicilin, ampicillin, macrolides and clindamycin, but sensitive to other 15 common antibiotics such as cephalosporin. Two strains of MRSA were found in patients with abscess. Conclusion In Chongqing, ET-producing SA is the common pathogenic bacteria of SSSS and impetigo, and most of SA strains produce both ETA and ETB.