In order to solve the problem of resistance of Pseudomonas aeruginosa to multiple antibiotics, it is an effective way to find inhibitors of P. aeruginosa efflux pump. In this study, 15 new ornithine peptidomimetic derivatives were designed and synthesized by changing the side chain structure of natural amino acids with PAβN, a dipeptide efflux pump inhibitor, and their synergic activity with aztreonam, a monocyclic β-lactam antibiotic, against P. aeruginosa was evaluated. Among them, the representative compound 12b not only enhanced the antibacterial activity of β-lactam antibiotics aztreonam, ceftazidime and meropenem, but also significantly enhanced the antibacterial action of macrolide antibiotics clarithromycin, showing a broad-spectrum synergic sensitization effect. In addition, compound 12b also has a good safety. Preliminary mechanisms suggest that 12b works by directly targeting the efflux transporter MexB. These results provide a new lead compound for the development of a new class of efflux pump inhibitors against P. aeruginosa.

The liver injury induced by Polygonum multiflorum Thunb. (PM) was investigated based on idiosyncratic hepatotoxicity model co-treated with lipopolysaccharide (LPS) at a non-hepatotoxic dose. Sprague-Dawley (SD) rats were intragastrically administered with three doses (18.9, 37.8, 75.6 g crude drug per kg body weight) of 50% alcohol extracts of PM alone or co-treated with non-toxic dose of LPS (2.8 mg·kg(-1)) via tail vein injection. The plasma alanine aminotransferase (ALT) and aspartate aminotransferase (AST) activities were assayed and the isolated livers were evaluated for histopathological changes. The dose-toxicity relationships of single treatment of PM or co-treatment of LPS were investigated comparatively to elucidate the idiosyncratic hepatotoxicity of PM. The results showed that no significant alterations of plasma ALT and AST activities were observed in the groups of solo-administration of LPS (2.8 mg·kg(-1), i.v.) or different dosage (18.9, 37.8 and 75.6 g·kg(-1), i.g.) of PM, compared to normal control group (P > 0.05); while significant elevations were observed in the co-administration groups of PM and LPS. Treatment with LPS alone caused slight infiltration of inflammatory cells in portal area but no evident hepatocytes injury. Co-treatment with LPS and PM (75.6 g·kg(-1), i.g.) caused hepatocyte focal necrosis, loss of central vein intima and a large number of inflammatory cell infiltration in portal areas. When further reduce the dosage of PM, significant increases of plasma ALT and AST activities (P < 0.05) were still observed in co-administration groups of LPS and PM (1.08 or 2.16 g·kg(-1)), but not in LPS or PM solo-administration groups. Nevertheless, the co-treatment of low dosage of PM (0.54 g·kg(-1)) with LPS did not induce any alteration of plasma ALT and AST. In conclusion, intragastric administration with 75.6 g·kg(-1) of PM did not induce liver injury in normal rats model; while the 2 folds of clinical equivalent dose of PM (1.08 g·kg(-1)) could result in liver injury in the LPS-based idiosyncratic hepatotoxicity model, which could be used to evaluate the idiosyncratic hepatotoxicity of PM.
Alanine Transaminase ; blood ; Animals ; Aspartate Aminotransferases ; blood ; Chemical and Drug Induced Liver Injury ; pathology ; Hepatocytes ; pathology ; Lipopolysaccharides ; Polygonum ; toxicity ; Rats ; Rats, Sprague-Dawley

OBJECTIVETo investigate the ectopic grafts of mouse testicular cells by observing the reconstruction of seminiferous tubules, colonization of spermatogenic cells and spermatogenesis using immunodeficient mice as recipients.

METHODSThe testes of newborn male ICR mice were digested to obtain single cell suspension. The cells were then mixed with matrigel and subcutaneously grafted into the dorsal region of the male nude mice. The mice were castrated after the operation and the grafts were dissected from 5 of the nude mice at 4, 6, 8 and 10 weeks, respectively. The success rates of transplantation and the graft diameters were calculated, and the structure of the reconstituted seminiferous tubules, colonization of the germ cells and spermatogenesis were observed by HE staining and immunohistochemistry.

RESULTSAll the mice recipients survived after the testicular cell transplantation. Within 10 weeks after the operation, tissue masses could be observed, with the diameter increased from (3.91 +/- 0.71) mm at 4 weeks to (6.69 +/- 0.50) mm. Neovascularization was detected at the surface of the masses and seminiferous tubule structures found in the grafts. The germ cells that developed from spermatogonia to round spermatids were observed, but with no sperm in the tubules. Germ cells, Sertoli cells and Leydig cells were identified by immunochemical detection of Mvh, Gata4 and P450Scc in the grafts at 8 weeks.

CONCLUSIONSeminiferous tubules could be ectopically reconstructed from suspension of neonatal mouse testicular cells. Ectopic grafting provided a preferable model for the studies on testis tissue engineering and interactions between testicular cells during testicular development and spermatogenesis.

Animals ; Male ; Mice ; Mice, Inbred BALB C ; Mice, Inbred ICR ; Mice, Nude ; Seminiferous Tubules ; cytology ; Sertoli Cells ; cytology ; transplantation ; Spermatids ; cytology ; Spermatogenesis ; Testis ; cytology ; transplantation ; Transplantation, Heterologous