[Cationic liposome ceftazidime combined with nano-hydroxyapatite/beta-tricalcium phosphate for treatment of chronic osteomyelitis of rabbits].

OBJECTIVE: To observe the effect of cationic liposomal ceftazidime (CLC) combined with nano-hydroxyapatite/beta-tricalcium phosphate (n-HA/beta-TCP) in the treatment of chronic osteomyelitis of rabbits. METHODS: Thirty healthy New Zealand white rabbits (4-6 months old; weighing, 2-3 kg) were selected to prepare the chronic osteomyelitis models. After 4 weeks, the gross observation, X-ray examination, and bacteriological and histopathological examinations were done; the models were made successfully in 27 rabbits. Of 27 rabbits, 24 were randomly divided into 4 groups (n = 6): only debridement was performed in group A; ceftazidime was given (90 mg/kg), twice a day for 8 weeks after debridement in group B; ceftazidime and n-HA/beta-TC were implanted after debridement in group C; and CLC and n-HA/beta-TCP were implanted after debridement in group D. Before and after treatments, X-ray examination was done, and Norden score was recorded. At 8 weeks after treatment, the specimens were harvested for gross observation and for gross bone pathological score (GBPS) using Rissing standard; half of the specimens was used for histological observation and Smeltzer scoring, the other half for bacteriological examination and calculation of the positive rate of bacteria culture. RESULTS: At 8 weeks after treatment, Norden score of group D was significantly lower than that of groups A, B, and C (P < 0.05), but no significant difference was found among groups A, B, and C (P > 0.05). At 8 weeks after treatment, sinus healed in groups C and D, but sinus was observed in groups A and B; the GBPS scores of groups C and D were significantly lower than those of groups A and B (P < 0.05). The Smeltzer scores of groups C and D were significantly lower than those of groups A and B (P < 0.05). The positive rates of bacteria culture of groups C (0) and D (0) were significantly lower than those of group A (25.0%) and group B (16.7%) (P < 0.05). CONCLUSION: CLC combined with n-HA/beta-TCP has good effect in treating chronic osteomyelitis of rabbits, and it has better effect in treating chronic osteomyelitis of rabbits than ceftazidime with n-HA/beta-TCP.

[Preparation of cationic vancomycin hydrochloride multivesicular liposomes and its quality].

OBJECTIVE: To prepare cationic Vancomycin hydrochloride multivesicular liposome (MVL) and to inspect its quality. METHODS: Cationic Vancomycin hydrochloride MVLs were prepared by double emulsion method, and the storing solution of Vancomycin was prepared. The analysis method of Vancomycin in vitro was established; the specificity, precision, and resorption rate were estimated. Reverse phase high performance liquid chromatography (RP-HPLC) was used to determine the concentration of Vancomycin, encapsulation efficiency, and release characteristics in vitro. The formulation and pharmaceutical process were optimized by single factor experiments and orthogonal experimental design with the factor of encapsulation efficiency as the criteria. The liposome morphology was observed by optical microscopy and transmission electron microscopy. The particle size and Zeta potential were determined by Malvern instrument. The stability was analyzed by dynamic analysis. RESULTS: An RP-HPLC method was established for the assay of Vancomycin. The analysis method was precise, simple, and reliable for the quality control of Vancomycin. Vancomycin hydrochloride MVLs were round and well-distributed. The average particle size and the encapsulation efficiency were 3.3 microm and 24.9%, respectively. Zeta potential was 24.53 mV, and 90.5% of Vancomycin hydrochloride was released after 264 hours in normal saline under 37 degrees C. Cationic Vancomycin MVLs were stored for 1 month at 4 degrees C, which mantained good stability. CONCLUSION: Cationic Vancomycin hydrochloride MVLs have good appearance, high encapsulation efficiency, good stability, and significant sustained release properties.

[Progress of liposomes as antibiotic carriers].

OBJECTIVE: To reviewe the research progress of liposomes as antibiotic carriers. METHODS: Domestic and abroad literature concerning liposomes as antibiotic carriers was reviewed and analyzed thoroughly. RESULTS: Liposomes as antibiotic carriers can significantly improve drug distribution, enhance antibacterial activity, and reduce the side effects of antibiotics during treatment. But it also has some problems, such as poor physical and chemical stabilities and low encapsulation efficiency. CONCLUSION: Liposomes as antibiotic carriers can reduce the drug toxicity, improve drug biodistribution, and pharmacokinetics, and bring the dawn to completely curing infections disease.

[A comparative study on effect of different defect diameters on healing in middle 1/3 tibia monolayer cortical bone defect mouse model].

OBJECTIVE: To compare the effect of different defect diameters on healing in the middle 1/3 tibia monolayer cortical bone defect mouse model so as to establish an animal model for bone tissue engineering study, mechanism study on bone defect repair, and gene therapy research. METHODS: Ten 8-week-old C57BL/6J mice, weighing (20 +/- 2) g, were randomly divided into 2 groups, 5 mice in each group. The middle 1/3 tibiae monolayer cortical bone defect model of 0.8 mm (group A) or 1.0 mm (group B) in diameter was established with burr drill. At 7, 21, and 28 days after modeling, the molybdenum target X-ray radiography was used to observe the defect repair; at 28 days, Micro CT and three-dimensional imaging were used to evaluate bone defect repair, and tibia specimens were harvested for HE staining. RESULTS: At 7 days after modeling, tibia fracture occurred in 5 mice in group B, no fracture in group A. X-ray films, Micro CT scan, and HE staining showed bony union in group A at 28 days. The quantitative analysis of trabecular bone by Micro CT showed that trabecular number, connectivity density, and bone volume in group A were significantly greater than those in group B (P < 0.05), mean of segmented region--mean 2 was significantly less than that in group B (P < 0.05), but no significant difference was found in trabecular separation and trabecular thickness between 2 groups (P > 0.05). CONCLUSION: The middle 1/3 tibia monolayer cortical bone defect mouse model of 0.8 mm in diameter is the ideal animal model for study repair mechanism of tibia defect or bone tissue engineering.