包裹在脂质体内部胰岛素的二级结构

目的以单纯胰岛素为对照，采用傅立叶红外光谱（Fourier transform infrared， FTIR）研究包裹在脂质体内部胰岛素二级结构的变化。方法分别对单纯胰岛素、胰岛素与空白脂质体混合物（样品I）及包裹胰岛素的脂质体（II）样品进行测定。结果样品I和样品II中胰岛素的FTIR谱图形状与单纯胰岛素相比基本一致，仅α-螺旋百分比略有下降（由36.09%分别下降到31.68%和31.45%），β-折叠百分比略有增加（由47.83%分别增加到53.29%和51.36%）。样品I和样品II中胰岛素的二级结构无明显差别（α-螺旋百分比为31.68%和31.45%，β-折叠百分比为53.29%和51.36%）。结论包裹在脂质体内部胰岛素的二级结构与单纯胰岛素相比无明显变化。     

Pharmacokinetics of paclitaxel-containing liposomes in rats

In animal models, liposomal formulations of paclitaxel possess lower toxicity and equal antitumor efficacy compared with the clinical formulation, Taxol. The goal of this study was to determine the formulation dependence of paclitaxel pharmacokinetics in rats, in order to test the hypothesis that altered biodistribution of paclitaxel modifies the exposure of critical normal tissues. Paclitaxel was administered intravenously in either multilamellar (MLV) liposomes composed of phosphatidylglycerol/phosphatidylcholine (L-pac) or in the Cremophor EL/ethanol vehicle used for the Taxol formulation (Cre-pac). The dose was 40 mg/kg, and the infusion time was 8 to 9 minutes. Animals were killed at various times, and pharmacokinetic parameters were determined from the blood and tissue distribution of paclitaxel. The area under the concentration vs time curve (AUC) for blood was similar for the 2 formulations (L-pac: 38.1±3.32 μg-h/mL; Cre-pac: 34.5±0.994 μg-h/mL), however, the AUC for various tissues was formulation-dependent. For bone marrow, skin, kidney, brain, adipose, and muscle tissue, the AUC was statistically higher for Cre-pac. For spleen, a tissue of the reticuloendothelial system that is important in the clearance of liposomes, the AUC was statistically higher for L-pac. Apparent tissue partition coefficients (K_p) also were calculated. For bone marrow, a tissue in which paclitaxel exerts significant toxicity, K_p was 5-fold greater for paclitaxel in Cre-pac. The data are consistent with paclitaxel release from circulating liposomes, but with efflux delayed sufficiently to retain drug to a greater extent in the central (blood) compartment and reduce penetration into peripheral tissues. These effects may contribute to the reduced toxicity of liposomal formulations of paclitaxel.     

In vivo efficacy of a novel double liposome as an oral dosage form of salmon calcitonin

A simple method for the preparation of the inner liposomes for double liposomes (DL) was developed. The encapsulation efficiency of erythrosine in liposomes prepared by this new method is superior to that of the previous method because of the concentration of the drug in the lipid membrane. To evaluate the usefulness of DL prepared by the glass‐filter method modified in this study as an oral dosage form of salmon calcitonin (SCT), a suspension of liposomes containing SCT was administered to rats at a dose of 10 μg SCT/kg. Each type of DL showed better efficacy than its inner liposomes alone. The decrease in plasma calcium level was dependent on the electrical charge and particle size of the inner liposomes. The hypocalcemic efficacy of DL encapsulating SCT‐loading cationic liposomes relative to that after subcutaneous administration of SCT at a dose of 1 μg/kg was 6.47%, which was the largest value obtained. These results indicated that not only the particle size but also the electrical charge of inner liposomes affect intestinal absorption. This study verified that the efficacy was increased because of the decrease in diameter of the inner liposomes and the use of lipid with a positive charge. These findings concluded that DL might be useful as an oral dosage form of SCT. Drug Dev. Res. 58:253–257, 2003. © 2003 Wiley‐Liss, Inc.     

荆豆凝集素修饰脂质体对小鼠口服吸收胰岛素的促进作用

目的研究荆豆凝集素(UEA1)修饰的胰岛素脂质体在小鼠胃肠道的吸收作用。方法采用碳二亚胺偶联法制备荆豆凝集素修饰的磷脂酰乙醇胺(PE)，将PE-UEA1参入胰岛素脂质体中制成凝集素修饰脂质体，并证实UEA1凝集活性不受影响。分别对正常小鼠及糖尿病模型小鼠灌胃给予350 u·kg^-1胰岛素的修饰脂质体溶液，用葡萄糖酶试剂盒测定小鼠血糖，并与同剂量普通胰岛素脂质体比较。结果对于正常小鼠，荆豆凝集素修饰脂质体在4 h使血糖降至初始水平的(84±15)%，8 h降至(78±11)%，12 h为(90±12)%。胰岛素普通脂质体几乎没有降糖作用，与生理盐水对照组相当。对于糖尿病模型小鼠，荆豆凝集素修饰脂质体在4 h使血糖降至初始水平的(73±7)%，8 h降至(74±9)%，12 h为(86±9)%。结论荆豆凝集素修饰的脂质体可能通过与M细胞表面特异性受体的结合促进大分子药物的胃肠吸收。     

Study and development of encapsulated forms of 4, 5′, 8‐Trimethylpsoralen for topical drug delivery

Trimethylpsoralen (TMP) is often used to treat skin diseases (i.e., psoriasis, vitiligo, etc.). This drug permeates moderately the skin barrier. In the present study, we investigated the effect of formulation on the improvement of TMP skin bioavailability. Three formulations were performed. Each form (liposomes, nanospheres, and EtOH solution) contained 0.05% of TMP. For each preparation, the quantity deposited on the skin surface was 250 µg (Q₀). The TMP percutaneous penetration through ex‐vivo human skin was processed by Franz^® cells (n=4) using a human albumin solution (1.4% w/v) as receiver medium. The percentages of the extracted TMP that permeated through the skin and that were retained in the skin over 24 h, were calculated with respect to Q₀. The values obtained were reported, respectively, as follows: EtOH solution (1.33 vs. 0.08%), liposomes (0.93 vs. 0.93%), and PLG‐nanospheres (0.79 vs. 3.01%). So, considering the correlation between the cumulated amounts of TMP permeated through the skin and the TMP stocked in the skin, the nanosphere form showed the higher quantity of TMP accumulated in the skin structures. On the other hand, the maximum value of the flux (ng/cm²/h) in the steady state of TMP incorporated in each formulation was at 6 h for all formulations: 173.5±1.06 (EtOH solution) > 120.4±1.06 (liposomes) > 93.82±0.88 (PLG‐nanospheres). These results indicate that the controlled release of TMP by incorporation in PLG‐nanospheres may increase drug content in the skin, while maintaining a minimal percutaneous absorption. Finally, this work shows that the PLG‐nanospheres could constitute a promising approach for controlling TMP release in order to maintain its topical activity. Drug Dev. Res. 61:86–94, 2004. © 2004 Wiley‐Liss, Inc.     

新型抗癌药依托泊苷脂质体的制备

 目的 制备依托泊苷脂质体，测定其含药量及包封率，对其体外释放及原料药的体外释放进行比较，并对脂质体灭菌后的稳定性进行考察。方法 采用薄膜-超声分散法制备依托泊苷脂质体，通过均匀设计优化处方，利用透析法测定其含药量及包封率，进行热压灭菌及⁶⁰Co灭菌两种灭菌方式，以粒径和包封率为指标考证灭菌后的稳定性。结果 按均匀设计的最优组合制备脂质体的含药量为（574.3±30.7）μg·mL^-1,平均包封率为（61.58±0.83）%，依托泊苷脂质体50 h累积释药（96.13±1.11）%,而其原料药3 h累积释药（97.10±1.84）%，热压灭菌的渗漏率比60Co灭菌的渗漏率高。结论 用薄膜-超声分散法制备的依托泊苷脂质体外观圆整，粒径小而均匀，体外释药达到了长效缓释的作用，⁶⁰Co灭菌后脂质体较稳定。     

Lipofectin介导bcl-xL反义寡核苷酸抑制鼻咽癌细胞增殖活性的研究

目的　观察并探讨阳离子脂质体 (L ipofectin,L ip)介导的 bcl- x L 反义寡核苷酸 (antisenseoligodeoxynucletide,ASODN)对鼻咽癌细胞株 CNE- 1、CNE- 2 Z细胞体外抑制增殖活性的影响。方法　人工合成硫代修饰型 bcl- x L 反义寡核苷酸 (ASODN) ,与 L ip混合制备成 L ip+oligodeoxynucletide(ODN)复合物 ,处理鼻咽癌细胞株 CNE- 1、CNE- 2 Z细胞 ,用 MTT比色法检测细胞存活状态 ;流式细胞术检测细胞凋亡。结果　 ASODN处理细胞 3 6小时 ,于 40 0 μm ol/ L 浓度条件下鼻咽癌细胞的增殖受到明显抑制 ,且这一抑制作用随着浓度的增加与时间的延长而加强 ,与硫代修饰型随机序列对照寡核苷酸 (sequence control ODN,SCODN)组及单独脂质体组比较 ,差异有显著性 (P<0 .0 5 )。结论　 bcl- x L 反义寡核苷酸可显著抑制鼻咽癌细胞株 CNE- 1、CNE- 2 Z细胞体外增殖活性 ,其抑制作用可能通过封闭 bcl- x L 基因表达实现 ,bcl- x L 反义寡核苷酸有可能成为一种潜在性的基因治疗药物用于鼻咽癌的治疗     

c-raf-1反义寡核苷酸对人卵巢癌细胞放射敏感性的影响

目的　探讨癌基因 c- raf- 1的反义寡核苷酸对人卵巢癌细胞放射敏感性的影响。方法　设立 c- raf- 1正义寡核苷酸组和非处理组 (仅加入等量的脂质体 )作对照 ,用 RT- PCR检测卵巢癌细胞处理前后 c- raf- 1表达水平的变化。用平板克隆形成试验检测人卵巢癌细胞株 SKOV3在脂质体 - c- raf- 1反义寡核苷酸作用前后受 6 0 Coγ射线不同剂量照射后的集落形成率。结果　 c- raf- 1反义寡核苷酸能抑制 c- raf- 1癌基因的表达 ,经脂质体介导的 c- raf- 1反义寡核苷酸作用的卵巢癌细胞经γ射线照射后其集落形成率较转染正义寡核苷酸组及单纯照射组明显下降 (P<0 .0 1) ,而转染 c- raf- 1正义寡核苷酸组的集落形成率与单纯照射组相比无明显差异 (P>0 .0 5 )。结论　 c- raf- 1反义寡核苷酸通过抑制 c- raf- 1的表达降低人卵巢癌细胞株 SKOV 3放射抗拒性。该作用可能与 c- raf- 1反义寡核苷酸抑制了引起细胞辐射抗拒的细胞信号转导途径有关     

Antitumor Immunity Induction by Intracellular Hyperthermia Using Magnetite Cationic Liposomes

Induction of antitumor immunity to T-9 rat glioma by intracellular hyperthermia using functional magnetic particles was investigated. Magnetite cationic liposomes (MCLs), which have a positive surface charge, were used as heating mediators for intracellular hyperthermia. Solid T-9 glioma tissues were formed subcutaneously on both femurs of female F344 rats, and MCLs were injected via a needle only into the left solid tumors (treatment side). The rats were then divided into two groups, which received no irradiation, or irradiation for 30 min given three times at 24-h intervals with an alternating magnetic field (118 kHz, 384 Oe). On the treatment side, the tumor tissue disappeared completely in many rats exposed to the magnetic field. The tumor tissue on the opposite side also disappeared completely, even though MCLs were not injected into the right solid tumors. To examine whether a long-lasting and tumor-specific immunity could be generated, the rats that had been cured by the hyperthermia treatment were rechallenged with T-9 cells 3 months later. After a period of transient growth, all tumors disappeared. Furthermore, immuno-cytochemical assay revealed that the immune response induced by the hyperthermia treatment was mediated by both CD8⁺ and CD4⁺ T cells and accompanied by a marked augmentation of tumor-selective cytotoxic T lymphocyte activity. These results suggest that our magnetic particles are potentially effective tools for hyperthermic treatment of solid tumors, because in addition to killing of the tumor cells by heat, a host immune response is induced.     

脂质体对喷昔洛韦经小鼠皮肤渗透的影响

 目的　研究脂质体对喷昔洛韦经小鼠皮肤渗透的影响。方法　采用薄膜分散法制备喷昔洛韦脂质体,采用改进的Franz扩散池体外经皮渗透实验技术,以高效液相色谱法测定皮肤接收液中、血液和皮肤内药物浓度。结果　喷昔洛韦脂质体凝胶在皮肤中的渗透系数及药物滞留量明显大于喷昔洛韦乳膏;在体条件下,1%喷昔洛韦脂质体最大皮肤内浓度是 1%喷昔洛韦乳膏的1.51倍;18h后1%喷昔洛韦脂质体皮肤内浓度是1%喷昔洛韦乳膏的1.94倍。结论　脂质体对喷昔洛韦经小鼠皮肤的渗透具有显著影响。