Hepatocyte-targeted delivery using ph-sensitive liposomes loaded with lactosylnorcantharidin phospholipid complex: preparation, characterization, and therapeutic evaluation in vivo and in vitro.

Liposomes loaded with lactosyl-norcantharidin phospholipid complex (LPC) were prepared, in which soybean phosphatidylcholine was used to improve the liposolubility of lactosyl-norcantharidin (Lac-NCTD). The pH-sensitive LPC liposomes (pH-LPC-lips) were obtained by electrostatic adsorption of the carboxymethyl chitosan onto the surface of the liposomes. The in vitro drug release of pH-LPC-lips and LPC-lips was investigated in dissolution media with pH ranging from 1.0 to 8.0. The in vitro antitumor activity and cellular uptake of Lac-NCTD and its liposomes to HepG2 cells were studied. The pH-LPC-lips demonstrated strong cytotoxicity against the cells and easily permeated the cell membrane. The in vivo antitumor activities of Lac-NCTD and its liposomes were evaluated in mice bearing H22 liver tumors. The pH-LPC-lips displayed the best tumor inhibitory effect. The optical imaging results indicated that Cy7- labeled pH-LPC-lips showed excellent hepatocyte specificity in H22 tumor-bearing mice. Therefore, pH-LPC-lips can be regarded as liver-targeting agents that combine targeting and active releasing.

Direct-method structure determination of the native azurin II protein using one-wavelength anomalous scattering data.

The one-wavelength anomalous scattering (OAS) X-ray diffraction data of azurin II, a copper-containing protein from Alcaligenes xylosoxidans were collected at the Photon Factory, Japan at a 'routine' wavelength of 0.97 A. The structure had been originally solved by the molecular-replacement method [Dodd, Hasnain, Abraham, Eady & Smith (1995). Acta Cryst. D51, 1052-1064]. As a technique of ab initio structure determination, the direct method [Fan, Hao, Gu, Qian, Zheng & Ke (1990). Acta Cryst. A46, 935-939] was attempted to break the phase ambiguity intrinsic to OAS data. The phases were then improved using the solvent-flattening method. The final electron-density map clearly shows most Calpha positions and many side chains and it is traceable without prior knowledge of the structure. It is concluded that the direct method is capable of phasing anomalous scattering data collected at one wavelength from moderate-sized native proteins (M(w) approximately 20 kDa) which contain copper or atoms with a similar scattering power.