Preparation, characterization and anticancer activity of norcantharidin-loaded poly(ethylene glycol)-poly(caprolactone) amphiphilic block copolymer micelles.

In this study, a novel amphiphilic block copolymer biomaterial - poly (ethylene glycol)-poly (caprolactone) (PEG-PCL), was used to entrap norcantharidin (NCTD), taking advantage of self-assembly theory. Dialysis and volatilization dialysis were used to prepare copolymer micelles. Drug-loaded micelles were compared with blank micelles in terms of their particle diameter, morphology and IR spectral characteristics. The results revealed that there was no significant difference in respect of morphology and IR spectrum, but particle size differed. Drug-loaded micelles had a smaller particle size than blank micelles. Three important factors influencing particle size, the drug loading content (LC) and the drug entrapment efficiency (EE) of the NCTD-loaded micelles, were studied. The results indicated that the method of preparation and the type of organic solvent had a significant influence on the size of the micelles. LC and EE were greatly affected by the ratio of NCTD to copolymer. In vitro release of NCTD from the conjugate micelles showed that its release rate depended on the pH of the phosphate buffer solution (PBS). The amount released was higher at lower pH than under neutral conditions. In vitro antitumor activity of the NCTD conjugate against human hepatoma (HepG2) cell line and human lung cancer (A549) cell line was evaluated by the MTT method. Micelles loaded with NCTD demonstrated greater and more satisfactory cell viability inhibition than the free drug. In vivo antitumor activity of drug-loaded micelles was investigated in mice bearing S180 mouse sarcoma. NCTD-loaded micelles displayed tumor inhibition effects, better than the free drug. As a new drug delivery system, copolymer micelles present many advantages including easy formulation, good water solubility, low toxicity and high treatment efficacy, and show great potential as carriers of hydrophobic drugs.

[Diagnostic value of 128-slice CT coronary angiography in comparison with invasive coronary angiography].

OBJECTIVE: To observe the diagnostic value of non-invasive 128-slice computed tomography coronary angiography (CTA) in comparison with invasive coronary angiography. METHODS: 128-slice CTA and invasive coronary angiography were performed in 78 unselected consecutive patients (63 patients with suspected coronary artery disease and 15 patients with previous coronary stenting, 56 males, mean age 61 +/- 10 years) and > 50% reduction of minimal lumen diameter was defined as significant coronary stenosis. RESULTS: Fifty-eight out of 879 segments (7%) from CTA were not assessable because of irregular rhythm, vessel calcification or tachycardia. Compared with invasive coronary angiography, segment-based analysis from the 821 segments showed the sensitivity by CTA was 87%, specificity 97%, PPV 83% and NPV 97%. Four out of 22 stents implanted in 15 patients were not assessable by CTA because of poor image quality. Compared with invasive coronary angiography, the sensitivity of diagnosing in-stent restenosis by CTA was 100%, specificity 77%, PPV 63% and NPV 100% for the remaining 18 stents. CONCLUSIONS: One hundred and twenty-eight-slice CTA has a high accuracy for detecting coronary artery disease and in-stent restenosis after coronary stenting and could be considered as a valuable noninvasive technique for screening coronary artery disease in suspected patients.