ABSTRACT
In bone tissue engineering, fabrication of scaffold materials that are biodegradable with regenerative functions is one of the most important research fields. Silk fibroin exhibits many favorable characteristics used as scaffold materials. Among them, hybrid silk fibroin/inorganic composites prepared by biomimetic mineralization have better biocompatibility, biomechanical properties, and biodegradability. At the same time, the hybrid silk fibroin/inorganic materials have much better osteoinduction and conduction properties than silk fibroin. Here, the recent advances in the preparation of silk fibroin/silica hybrid materials by combination or biomimetic silicification are reviewed, and the future research prospects of silicification of silk fibroin are discussed.
ABSTRACT
OBJECTIVE:To study the correlation between antibacterials amount and drug resistance of Echerichia coli,and to provide reference for clinical use of antibacterials. METHODS:Retrospective review was used to calculate DDDs of antibacterials and resistance rate of Escherichia coli to 11 kinds of antibacterials each quarter. The correlation analysis was carried out using the SPSS 13.0 statistical software. RESULTS:The resistance rates of E. coli to piperacillin/tazobactam,cefoperazone/sulbactam and le-vofloxacin were with upward trends,and the others showed downward trends. The resistance rates of E. coli to meropenem and imi-penem/cilastatin appeared in 2014,increasing from 0 to 8.8% and 9.4%,respectively. DDDs of them were significantly correlated to drug resistance of E. coli,showing positive correlation(r=0.915,0.793,P<0.01). DDDs of piperacillin/tazobactam was signif-icantly correlated to resistance rate of E. coli(r=0.807,P<0.01),while that of ceftazidime was negatively correlated to resistance rate of E. coli(r=-0.672,P<0.05). There was no statistical significance in resistance rate of E. coli to other 7 kinds of antibacte-rials. CONCLUSIONS:There are some correlations between the DDDs and resistance rates. We should strengthen the monitoring of bacterial resistance and the management of rational application of antibacterials.
ABSTRACT
Preparation and in vitro/in vivo evaluation of gestodene [GEST] intravaginal ring [IVR] formulations which can release a constant dose of GEST during 3 weeks were investigated. In present study a reservoir gestodene intravaginal ring, including a gestodene silicone elastomer core and the non-active silicone layer, was reported, which was manufactured by reaction injection moulding at 80[degree]C for 20 min. The raw materials compatibility experiments showed that the silicone elastomer core carrier wouldn't interact with drugs. In vitro release samples were determined by HPLC and the experiment was performed under sink conditions. The equation of cumulative release verse time was Y=64.76x+5.44 [r=0.9998], performing zero-order release at about the target dose of 60 [micro]g/day over 21 days. Drug release increased with temperature elevating from 45 to 55[degree]C, which could be attributed to optimizing the prescription. In addition, the pharmacokinetic and safety studies of gestodene intravaginal ring were evaluated in female New Zealand White rabbits. The GEST in plasma was analyzed by LC-MS/MS and the results proved that the correlation between in vitro and in vivo was relatively well
ABSTRACT
This study taking gestodene (GEST) as a model, investigated the factors affecting reservoir-type intravaginal ring (IVR)'s drug release. This paper reported a gestodene intravaginal ring of reservoir design, comprising a gestodene silicone elastomer core encased in a non-medicated silicone sheath, separately manufactured by reaction injection moulding at 80 degrees C and heating vulcanization at 130 degrees C is reported. The test investigated the factors affecting drug release through a single variable method, taking the drug release rates of 21 days as standards. When changing the thickness of the controlling sheath outside, the ratio of the first day of drug release and mean daily release (MDR), named the relatively burst effect, is closing to 1 with the thickness of controlling sheath increasing, while the 1.25 mm sheath corresponding to 1.04 controlled the burst release effectively; a positive correlation (r = 0.992 2) existed between the average drug release (Q/t) and drug loading (A) within a certain range. The C6-165 controlling sheath with high solubility of GEST is easier to achieve controlled release of the drug; GEST crystalline power is more effective to implement controlled release of drugs among difficent states of the drug. A 1/4 fractional segment core gives a relatively burst effect of 1.76, while the 1/1 and 1/2 are 1.93 and 1.87 separately, at the same drug loading, concluding that use of a fractional segment core would allow development of a suitable GEST reservoir IVR. In summary, GEST reservoir-type IVR could be adjusted by the thickness of controlling sheath, the loading of drug, the material properties of controlling sheath, the dispersion state of drug, the additive composition and structure of intravaginal ring, to control the drug release behavior and achieve the desired drug release rate.