ABSTRACT
cRGD-carboxymethyl chitosan-palmitic acid (cRGD-CMCh-PA) was synthesized and a pHsensitive paclitaxel-loaded cRGD-CMCh-PA micelles (PTX-cRGD-CMCh-PA) was prepared with the film dispersion method; related substances were characterized by FT-IR and 1H NMR. PTX-cRGD-CMCh-PA micelles were studied with the particle size distribution, zeta potential, morphology and release behavior in vitro was investigated by the method of equilibrium dialysis. In vitro cytotoxicity of different formulations on A549 cells was tested by MTT assay. The uptake process of micelles was explored using confocal microscopy and a live cell station was used to observe the dynamic phagocytosis. The subcutaneous and orthotropic tumor models were built to study the distribution of DiR-labeled micelles by near-infrared fluorescence (NIR) imaging system. The FT-IR spectra and 1H NMR spectra confirmed the successful conjugation of cRGD-CMCh-PA polymer and the degree of carboxymethyl and the palmitic acid grafted on chitosan were 45.0% and 15.0%. PTX-cRGD-CMCh-PA micelles were prepared with particle size of (162.9±1.5) nm, zeta potential of +26.3 mV and encapsulation efficiency and the drug loading of 99.67% and 28.5%, respectively. The micelles released slowly in pH 7.4 whose release curves were accorded with the Higuchi equation; they had an initial burst effect in second hours and showed a pH sensitive release behavior in pH 5.3. The IC50 of PXT-CMCh-PA and PTX-cRGD-CMCh-PA were 2.077 μg·mL-1 and 0.876 μg·mL-1, respectively. The cells uptake process of micelles in A549 cells revealed that the micelles were mainly co-located with lysosome and PTX-cRGD-CMCh-PA showed much better targeting effect. The NIR fluorescence imaging results showed that the micelles had a good targeting effect on both subcutaneous and orthotropic tumors. In this study, a novel copolymer cRGDCMCh-PA was synthesized with a sustained and pH-dependent drug release activity which would potentially become a new carrier for hydrophobic drugs.
ABSTRACT
<p><b>OBJECTIVE</b>To explore the relationship between the polymorphism of HLA-DRB1*, DQB* genes and the susceptibility of pneumoconiosis.</p><p><b>METHODS</b>1:1 case-control study was adopted. one hundred and thirteen cases of I grade pneumoconiosis were investigated. The control group were workers exposed to dust, who were the same sex, nationality, work place, time of beginning exposure and the cumulative exposure ages not over 2 years. PCR-SSP was used to detect 9 alleles in HLA-DRB1*, DQB1*. Information on related factors of pneumoconiosis was collected using a questionnaire. Univariate and multivariate logistic regression analysis were carried out with 1:1 case-control methodology.</p><p><b>RESULTS</b>The frequency of HLA-DRB1*08 allele in case group was significantly higher than that of the controls (OR: 6.000; 95% CI: 1.9060 - 18.9414). The frequencies of HLA-DRB1*09, HLA-DQB1*06 in case group were significantly lower than those of the controls (OR: 0.259, 0.300; 95% CI: 0.1436 - 0.6268, 0.1149 - 0.5837 respectively). There were significant relationship between HLA-DRB1*08, HLA-DRB1*09, HLA-DQB1*06 alleles and pneumoconiosis after adjusting age, smoking, beginning age of exposure and cumulative length of exposure with multivariate logistic regression analysis (OR: 7.804, 0.225, and 0.269; 95% CI: 2.077 - 29.307, 0.083 - 0.609 and 0.117 - 0.613 respectively. Survival analysis showed that HLA-DQB1*06 allele was a protective factor and HLA-DRB1*08 allele was a risk factor for affecting pneumoconiosis latent period.</p><p><b>CONCLUSION</b>HLA-DRB1*08 allele may be the susceptible risk gene for pneumoconiosis. HLA-DQB1*06 may be the protective gene against developing pneumoconiosis.</p>