包裹外毒素Ⅲ的VEGF-脂质体靶向杀伤肿瘤血管内皮细胞的实验研究

目的 利用包裹绿脓杆菌外毒素单元Ⅲ的VEGF(血管内皮生长因子)-脂质体于体外靶向杀伤肿瘤血管内皮细胞。方法 通过结合实验。验证VEGF连接脂质体对肿瘤血管内皮细胞具有特异结合能力。利用体外细胞毒实验(MTT)方法，检测外毒素单元Ⅲ及靶向脂质体包裹的单元Ⅲ对肿瘤血管内皮细胞的杀伤作用。结果 连有VEGF的脂质体可与表达血管内皮生长因子受体(VEGFR)的肿瘤血管内皮细胞特异性结合。结合率可达非特异性脂质体的2倍。在去除外毒素单元Ⅰ和Ⅱ后，单元Ⅲ的细胞毒作用消失。但包裹单元Ⅲ的VEGF-脂质体可特异性杀伤肿瘤血管内皮细胞。结论 VEGF-脂质体可特异性地识别肿瘤血管内皮细胞。并作为良好载体将绿脓杆菌外毒素单元Ⅲ带入细胞，实现其杀伤作用，可望成为一种有效的抗肿瘤物质。     

Cationic Lipid-Based Gene Delivery Systems: Pharmaceutical Perspectives

Gene delivery systems are designed to control the location of administered therapeutic genes within a patient's body. Successful in vivo gene transfer may require (i) the condensation of plasmid and its protection from nuclease degradation, (ii) cellular interaction and internalization of condensed plasmid, (iii) escape of plasmid from endosomes (if endocytosis is involved), and (iv) plasmid entry into cell nuclei. Expression plasmids encoding a therapeutic protein can be, for instance, complexed with cationic liposomes or micelles in order to achieve effective in vivo gene transfer. A thorough knowledge of pharmaceutics and drug delivery, bio-engineering, as well as cell and molecular biology is required to design optimal systems for gene therapy. This mini-review provides a critical discussion on cationic lipid-based gene delivery systems and their possible uses as pharmaceuticals.     

Phase I and pharmacologie study of liposomal daunorubicin (DaunoXome)

Summary We have completed a phase I and pharmacology study of liposomally-encapsulated daunorubicin (DaunoXome). Of 32 patients entered, 30 were evaluable. No toxicity was encountered at the initial doseescalation steps from 10 to 60 mg/m². At 80 mg/m², two patients manifested grade 2 neutropenia. At least grade 3 neutropenia occurred in all patients receiving 120 mg/m². Alopecia and subjective intolerance were mild. Cardiotoxicity was not observed except for an episode of arrhythmia in a patient with lung cancer and prior radiation. Only one minor objective response was observed in this population of refractory solid tumors. Pharmacokinetics differed from those of the free drug with no detection of daunorubicinol. We recommend future phase II studies with a dose of 100 mg/m² in previously treated and 120 mg/m² of DaunoXome in previously untreated patients with solid tumors.EDW is supported in part by ACS award 92-14-1     

三氧化二砷脂质体的制备及其对鼠脑胶质瘤的影响

目的研究三氧化二砷（As2o3）脂质体注射液对大鼠体内C6胶质瘤细胞凋亡的影响。方法采用超声薄膜分散法制备As籼脂质体，将126只成瘤大鼠分为As2O3脂质体组、As2O3组、生理盐水组。原子荧光法检测注射As2O3脂质体和As2O3后大鼠脑组织中As2O3浓度。从电镜、TUNNEL和大鼠生存时间等方面研究As2O3脂质体对C6胶质瘤的影响。结果As203，脂质体提高了As2O3的血-脑屏障通过。电镜和TUNEL检测显示：As203脂质体组细胞凋亡率给药后3d为（13．53±1．68）％，7d为（20．03±0．79）％，多于As2O3组和盐水组。动物生存时间亦优于其他两组。结论超声薄膜分散法是制备As2O3脂质体的较好方法。As203脂质体可较As203更明显地诱导鼠脑胶质瘤细胞凋亡，延长载瘤鼠的生存期。     

Kupffer cell depletion in vivo results in preferential elimination of IgG aggregates and immune complexes via specific Fc receptors on rat liver endothelial cells.

In the present study we have investigated the clearance kinetics and tissue distribution of monomeric (m) IgG and soluble aggregates of IgG (AIgG) and immune complexes (IC) in normal and Kupffer cell (KC) depleted rats. In normal rats, clearance of mIgG occurred in a biphasic manner with a first half-life (T1/2) (T1) of 36.3 +/- 6.3 min and a second T1/2 (T2) of 168.4 +/- 4.7 min. AIgG composed of 20-27 IgG molecules per aggregate were cleared significantly faster than mIgG with a T1 of 2.5 +/- 0.1 min and a T2 of 32.5 +/- 5.6 min. KC depletion did not have a significant effect on the clearance rate of mIgG (T1: 33.4 +/- 8.9 min; T2; 159.5 +/- 12.5 min), while clearance of AIgG was delayed significantly with T1 4.8 +/- 0.7 min and T2 41.2 +/- 3.2 min. Eight minutes after injection, 77% of AIgG was found in the liver in normal rats while 62% was found in the liver of KC-depleted rats. Double immunofluorescence studies indicated that AIgG in the liver was associated with KC and endothelial cells (EC) in normal rats. In KC-depleted rats, AIgG was strongly associated with EC. A similar staining pattern was observed when IgG-immune IC were administered. The clearance of AIgG in KC-depleted rats was inhibited fully by pre-administration of high concentrations of IgG but not by pretreatment with IgA. asialofetuin (ASFe) or ovalbumin (OVA). Aggregated F(ab')2IgG was cleared with a comparable rate to mIgG from the circulation, again suggesting Fc gamma receptor-mediated elimination of AIgG by EC. There was a reduced degradation of AIgG in rats depleted of KC as compared with normal rats. These data suggest binding and degradation of AIgG by EC in vivo.     

Scintigraphic visualization of intrathecal liposome biodistribution

Background: Liposomes containing local anaesthetics have been administered intrathecally and in the epidural space. Poor attention has been given to the pharmacokinetics of liposomes as drug carriers. Therefore, we observed the biodistribution of liposomes after intrathecal injection in rats by scintigraphic imaging during 24 h.
Methods: We administered ⁹⁹Tc-labeled multilamellar (MLV) and small unilamellar vesicles (SUV) of defined size and volume dispersities into the cerebrospinal fluid at the lumbar level. Those vesicles were free of contamination by radiolabeled colloids as visualized by light and electron microscopy and of neurotoxic products from phosphatidylcholine hydrolysis and peroxidation, both during the preparation process and after 24 h incubation in cerebrospinal fluid at 37°C in vitro.
Results: SUV immediately diffused from the lumbar site of injection to the head and were cleared between 1 and 24 h after injection. MLV were cleared more slowly from the spinal space and appeared in the head region 1 h after injection where they accumulated up to 24 h. These differences were explained in terms of vesicle sizes and volumes. SUV with 0.05 μm diameters were rapidly absorbed into the blood through the arachnoid granulations. In contrast, particles larger than the upper size limit of the arachnoid granulations permeability (±8 μm) could accumulate in the head with a slow elimination rate.
Conclusion: This difference in clearance from the intrathecal space outlines the importance of defining the size of the liposomes, the distribution of a tracer or a drug inside the liposomal preparation, the chemical stability and the absence of toxic degradation products of liposome formulations before clinical use.     

阿苯达唑脂质体治疗包虫病的初期临床观察

目的：评价阿苯达唑脂质体（L－ABZ）口服液的临床疗效及药物副作用，为该药的临床应用提供依据。方法：选择53例包虫病患者，分为3组：A组为单纯服药组（35例），连续口服L－ABZ 3－6个月；B组为包虫囊肿穿刺前后服药组（4例），穿刺前3－7d开始服药，穿刺后连服1个月；C组为手术前后服药组（14例），术前3－7d开始服药，术后可进食水后即开始服药，疗程1个月。3个治疗组服药剂量均为每天10mg/kg，2次／d。同时动态随访病人服药前后的血常规、肝肾功、胸部X线片、B超或CT以及病人对药物的毒副反应。用治愈率、有效率、部分有效率和无效率来衡量A组的疗效。以复发率（观察至少1年）来判断B、C组的疗效。结果：A组治愈16例（45．7％），有效9例（25．7％），部分有效6例（17．1％），无效4例（11．4％），总有效率88．6％；B组、C组随访时间1－3年，尚无复发。临床药物治疗的53例服药病人中，尚未见因药物的副反应而终止治疗的病例。结论：阿苯达唑脂质体（L－ABZ）口服液对包虫病病人疗效较为肯定，毒副反应轻，患者能够长期服用，尤其适用于某些不宜施行手术治疗或复杂的包虫病例。     

Preparation and evaluation of temperature sensitive liposomes containing adriamycin and cytarabine

Temperature sensitive liposomes (TSL) containing adriamycin (ADM) and cytarabine (Ara-C) were prepared. ADM and Ara-C were selected as model compounds of amphiphilic and hydrophilic drug, respectively. Encapsulation efficiency of ADM entrapped into TSL was about twice greater than that of Ara-C. It might be due to different polarity of the drugs. Lipid compositions of TSL had no effect on the encapsulation efficiency of drugs. Thermal behavior of TSL using a differential scanning calorimetry (DSC) was also investigated. Phase transition temperature (T_c) of TSL was dependent on the lipid compositions of TSL.ADM broadened thermogram of TSL but Ara-C did not. However, T_c of TSL was not changed by any drug. Release rate of drugs was highly dependent on temperature. The release profile of ADM was similar to that of Ara-C. The maximum release rate of drugs from TSL was occurred at the near T_c and observed at 39–41°C for DPPC (Dipalmitoylphosphatidylcholine) only, 52–54°C for DSPC (Distearoylphosphatidylcholine) only, 41–43°C for DPPC and DSPC (3∶1), and 43–45°C for DPPC and DSPC (1∶1), respectively. Effect of human serum albumin (HSA) on the release rate of ADM was investigated. HSA had no significant effect on the release of ADM below T_c. However, ADM release from TSL was increased at the near and above T_c. The HSA-induced leakage of drug may result from the interaction of liposomal constituents with HSA structure at the near T_c. From the fact that the release profiles of ADM from freshly prepared TSL and stored TSL for 1 week at 4°C was not changed, the TSL was considered to be stable for at least 1 week at 4°C. Based on these findings, TSL may be useful to deliver drugs to preheated target sites due to its thermal behaviors.     

Therapeutic effects of liposomal adriamycin in combination with tumor necrosis factor-alpha.

Liposomes as drug carriers in cancer chemotherapy have attracted considerable interest. To enhance the therapeutic effect of Adriamycin entrapped in liposomes (Lip-ADM) on human solid tumors, we investigated the therapeutic effects of Lip-ADM in combination with recombinant human tumor necrosis factor-alpha (rTNF-alpha), which is known to have specific effects on tumor vasculature. rTNF-alpha or saline solution was injected intravenously into nude mice bearing a human colon cancer strain, HC-1, at 1 hour before intravenous administration of Lip-ADM. The significant therapeutic effect of Lip-ADM in combination with rTNF-alpha was demonstrated by the evaluation with tumor growth curve and the actual tumor weights, in comparison with groups of mice treated with saline solution, rTNF-alpha alone, or with a Lip-ADM after saline. Levels of Adriamycin in tumor tissue in the Lip-ADM in combination with rTNF-alpha-treated group were higher than those in Lip-ADM with saline solution-treated group.