The drug-resistant mechanism of clinical non-fermenting bacilli producing IMP-1 metalloenzyme / 生物医学工程学杂志

A total of 50 clinical imipenem-resistant isolates of Pseudomonas aeruginosa and Acinetobacter baumannii were subjected to the ceftazidime-2- mercaptoethanol -double-disk synergy test and to the PCR assays with primers specific for bla(IMP-1). After the process of sequencing the positive one to identify the results, PCR analysis was conducted with primers specific for class 1 integrons. For synergy test, 28 isolates gave positive results, among which were 27 Pseudomonas aeruginosa and Acinetobacter baumannii. Only one Pseudomonas aeruginosa was found to carry bla(IMP-1), and bla(Int1) at the same time. This is the first ascertainment of IMP-1 producing Pseudomonas aeruginosa isolate carrying bla(IntI1) in West China, which is of significance to the research on the clinical spread of these drug-resisitant genes.

Investigation of biodegradable materials as polymeric gene carriers / 生物医学工程学杂志

This is a study on the biodegradable polymers as gene controlled-released coatings for gene transfer. The PELA (poly (Dl-lactic acid)-co-poly (ethylene glycol), and PLGAE (poly (lactic acid)-co-poly (ethylene glycol)-co-poly (glycolic acid) random copolymer) were synthesized and prepared as the coatings of plasmid pCH110 in the transfection. All kinds of factors affecting the loading efficiency, cytotoxicity, transfection efficiency and the course of the degradation and release in vitro were discussed. The average diameters of microspheres of PELA and PLGAE were 1-3 microm and 0.72 microm respectively. The loading efficiency levels of them were 62% and 70% respectively. The transfection efficiency levels of two kinds of pCH110 delivery system for COS-1 cells were higher and two of them had few cytotoxicity. After transfection, the X-gal assay was performed and reported positive for 96 h. The biodegradable polymeric materials as gene carriers possess their potential superiority.

Functional Effects of LasR/RhlR on Pseudomonas aeruginosa Biofilm Development and Lung Infections in Mice / 生物化学与生物物理进展

New strategies are needed for prevention of Pseudomonas aeruginosa (P. aeruginosa) infections, a widespread disease caused by P. aeruginosa with strong drug resistance. The immunoprotective capacity of the receptor of autoinducers protein LasR/RhlR was examined in the BALB/c mice. At first, specialized expression plasmids were developed to facilitate expression of LasR/RhlR proteins in Escherichia coli (E. coli). Then, biofilms were grown from clinical isolated P. aeruginosa PA0305 to investigate the relative contributions of cell signaling for biofilm formation. Morphological characters of biofilm were quantified using Image-Pro Plus software. Fluorescence analysis demonstrated that cell signal molecule LasR/RhlR significantly (P ＜ 0.05) influenced development of P. aeruginosa biofilm. Active immunization of mice with LasR/RhlR was found to provide significant protection against homologous challenge with P. aeruginosa in mice lungs. In 10 days after lungs inoculation, the bacterial clearance rate of the immunized mice was clearly higher than that of non-immunized groups on the basis of microbiological and histological assays. The protective effects of immunization with LasR and Rh1R together were the same as the result of LasR or Rh1R immunized mice alone. These data indicate that the manner ofLasR, Rh1R or both is an important determinant of immunoprotection in mice lungs infection.