ABSTRACT
Objective To investigate the effects of azithromycin and clarithromycin on biofilm formation of Pseudomonas aeruginosa.Methods The minimal inhibitory concentrations (MIC) of azithromycin,clarithromycin,ceftazidime,ciprofloxacin and gentamicin against 4 strains of Pseudomonas aeruginosa (ATCC 27853,PA1,PA2 and PA3) were determined by broth microdilution method.The biofilm formation of Pseudomonas aeruginosa was identified by silver dyeing method on the biofilm model with medical microporous membranes in vitro.The effects of azithromycin and clarithromycin on the adhesion of biofilm were detected by crystal violet staining.The synergistic bactericidal effects of azithromycin and clarithromycin with ceftazidime,ciprofloxacin or gentamicin were detected by thiazolyl blue method respectively.Results The MIC values of Pseudomonas aeruginosa ATCC 27853,PA1,PA2 and PA3 for azithromycin,clarithromycin,cefiazidime,ciprofloxacin and gentamycin were 32,64,1,≤0.125 and 0.25 μg/mL;32,256,8,0.25 and 1 μg/mL;64,128,＞ 256,32 and 2 μg/mL and 64,128,8,2 and 0.25 μg/mL.The results of silver staining showed that the microfiltration membranes of all the four P.aeruginosa cultures appeared to be grayish black,thick and dense,and cotton-like.Compared with the control group in which no antibacterial drugs were added,both azithromycin and clarithromycin (1/16 or 1/4 MIC) reduced significantly the adhesion of the 4 strains of Pseudomonas aeruginosa (ATCC 27853,PA1,PA2 and PA3) on the microporous membrane (Pall ＜ 0.05).Compared with the use of 1 MIC of ceftazidime,ciprofloxacin or gentamycin alone,the combination of anyone of the four antimicrobial drug with azithromycin or clarithromycin (1/16 MIC) reduced the counts of viable bacteria on each biofilms with significant differences (P all ＜ 0.01).Conclusion Azithromycin and clarithromycin could effectively inhibit the biofilm formation of Pseudomonas aeruginosa and may present synergistic effects combined with cefiazidime,ciprofloxacin or gentamicin.
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Objective To evaluate the effects of biological rhythm disturbance on sedation induced by propofol in rats.Methods Thirty-two adult male Sprague-Dawley rats,weighing 180-220 g,were randomly divided into 4 groups (n =8 each) using a random number table:circadian rhythm + administration during night-time group (group CN),circadian rhythm + administration during day-time group (group CD),biological rhythm+administration during night-time group (group BN),and biological rhythm+administration during day-time group (group BD).In CN and CD groups,the rats were fed for 2 weeks in the experimental boxes in a 12 (7:00-19:00):12 h (19:00-7:00) light:dark cycle.While the rats were fed for 2 weeks in the experimental boxes in a 24 h light cycle.Propofol 75 mg/kg was intraperitoneally injected at 14:00 in CN and BN groups,or at 22:00 in CD and BD groups.The duration of loss of righting reflex was recorded.At 20 min after recovery of righting reflex,the cognitive function was assessed.The latency of passive avoidance was measured at 6,12,24 and 48 h after training.Results Compared with group CN,the duration of loss of righting reflex was significantly shortened,and the latency of passive avoidance was prolonged at 12 and 24 h after training in group CD,and the duration of loss of righting reflex and latency of passive avoidance at 12 and 24 h after training were shortened in group BN.Compared with group CD,no significant change was found in the duration of loss of righting reflex,and the latency of passive avoidance was significantly shortened at 24 h after training in group BD.There was no significant change between BN group and BD group in the duration of loss of righting reflex and latency of passive avoidance.Conclusion Biological rhythm disturbance can counteract circadian rhythmproduced effects on sedation induced by propofol in rats.
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Microbial metabolic engineering and synthetic biology are important disciplines of microbial technology nowadays. Microbial cells are fast growing, easy to be cultivated in large scale, clear in genetic background and convenient in genetic modification. They play an important role in many domains. Microbial cell factory means an artificial microbial metabolic system that can be used in chemical production. The construction of a microbial cell factory needs transferring of multiple genes or a whole metabolic pathway, which may cause some problems such as metabolism imbalance and accumulation of mesostates. This review focuses on the regulation strategies of different levels involving simultaneous engagement of multiple genes. Future perspectives on the development of this domain were also discussed.
Subject(s)
Bacteria , Genetics , Fungi , Genetics , Gene Expression Regulation , Gene Regulatory Networks , Genetics , Genetic Engineering , Industrial Microbiology , Metabolic Engineering , Methods , Metabolic Networks and Pathways , GeneticsABSTRACT
<p><b>OBJECTIVE</b>To increase the reproduction efficiency of Iris plants.</p><p><b>METHOD</b>Pollen viability, stigmatic receptivity, the color of anther and stigma of 5 Iris plants were observed during blooming.</p><p><b>RESULT</b>1. The highest pollen viability was in 4 hours after blooming; 2. The stigmatic receptivities of I. sichuanensis, I. leptophylla, I. lactea and I. goniocarpa were strong in 4 hours after blooming, while that of I. lactea var. chinensis was strong in 2 hours after blooming; 3. The color of anther could reflect the pollen viability, but could not indicate the viability level; 4. The stigma color could not reflect the receptivity of stigma.</p><p><b>CONCLUSION</b>The optimum artificial pollination time of these five species were 12:00 -14:00.</p>