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@# Objective To study the effect of low frequency on drug release from improved PLGA microcapsules, and investigate the possibility of utilizing PLGA microcapsules as the carrier of ultrasound targeted drug delivery system to deliver drug into brain. Methods Doxorubicin loaded poly (D,L lactic-co-glycolic acid) (PLGA) microcapsules were prepared via double emulsion solvent evaporate method and coated with either chitosan or gelatin. In vitro drug release profile and the drug release rate under the exposure of low frequency pulsed ultrasound (25 kHz) and continuous wave ultrasound (35.1 kHz) were assayed. Results The coating with chitosan or gelatin can depress the burst of drug release. The drug release rate from uncoated and chitosan-coated microcapsules did not changed with the exposure of ultrasound, and the rate of gelatin-coated microcapsules did increased. The effect of pulsed ultrasound was stronger than that of continuous ultrasound. Conclusion The drug release from gelatin-coated PLGA microcapsules can be controlled and triggered by 25 kHz pulsed ultrasound, which may be a potent carrier of targeting drugs into brain.
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Objective To investigate the efficacy and mechanism of subcutaneously given recombinant Der p 2 entrapped PLGA nanoparticles(DEPN) on mouse model with allergic airway inflammation.Methods 40 BALB/c mice were randomly divided into 5 groups,group A(normal control) were treated with saline(100 ?l) all the time,groups B,C,D and E were sensitized intraperitoneally with crude dust mite extracts(10 ?g) and then subcutaneously treated respectively with PBS(100 ?l),2 mg empty PLGA(EP),100 ?g rDer p 2,and 2 mg DEPN(loaded with 100 ?g rDer p 2) for 3 times,once per day,followed by intranasal challenge of 50 ?g rDer p 2.One day post challenge,mice were sacrificed and bronchoalveolar lavage fluid(BALF) was collected.Number of the total cells and eosinophils was determined,and airway inflammation and mucus secretion were analyzed by haematoxylin and eosin(H&E) staining and periodic acid-Schiff(PAS) staining.Level of cytokines in the supernatant of splenocyte culture was assayed by ELISA.Level of rDer p 2 specific IgG2a and IgE in the sera was determined by ELISA.Results The lung histology showed development of eosinophil infiltration in the airway of mice in groups B and C.The lung inflammation and mucus secretion in groups D and E were significantly alleviated than that of groups B and C.Number of total cells(63.50?5.12) andeosinophils(15.32?3.04) in BALF decreased in group B.Compared with group B,the number of total cells in groups D(55.3?5.20) ? 104 /ml and E(41.00?4.91) ?104 /ml greatly decreased(P