流感疫苗壳聚糖脂质体的制备工艺

目的在流感疫苗脂质体的基础上制备壳聚糖脂质体载药微粒,建立流感疫苗壳聚糖脂质体的制备工艺．方法采用薄膜分散法制备流感疫苗脂质体,以不同N/P比（壳聚糖中的氮和卵磷脂中的磷比值）制备壳聚糖载药微粒．观察形态并测定其平均粒径、粒度分布、包封率与结合率．通过对比不同N/P比制备壳聚糖载药微粒的包封率与结合率等指标,确定流感疫苗壳聚糖脂质体的制备工艺．结果流感疫苗脂质体形态均呈圆或椭圆形,粒度分布较均匀,壳聚糖包覆后脂质体仍为圆形,平均粒径由2．14μm增加到4．05μm．壳聚糖包覆前后流感疫苗脂质体平均包封率由80．41％变为84．37％．比较6种不同N/P比流感疫苗壳聚糖脂质体的结合率,当N/P为5：1时,为壳聚糖与脂质体孵育的最佳比例,结合率为19．40％．结论壳聚糖包覆后脂质体仍接近圆形,粒径增加,包封率提高,当N/P为5：1时,为壳聚糖与脂质体孵育的最佳比例．     

不累及腋臭手术部位的间擦疹型手足综合征一例国际首报

【摘要】 患者女,25岁,因手足、腋下和腹股沟红斑水疱伴疼痛反复1个月就诊。7年前患者因腋臭双腋下曾行小切口汗腺切除术。1个月前因颈部滑膜肉瘤（ⅡB期）术后行多柔比星脂质体化疗,3次化疗期间,出现手足、腋下和腹股沟红斑水疱伴疼痛,皮损逐次加重。皮肤科检查：双手掌、足跖及腋下、腹股沟等间擦部位可见大片水肿性红斑,边界较清楚,上有粟粒至黄豆大小水疱,可见糜烂;皮疹处皮温高,触痛明显,尼氏征阳性;双腋下行小切口腋臭手术的部位无皮损,无疼痛。腋下皮损组织病理检查：基底层下水疱形成及部分汗腺坏死。诊断：多柔比星脂质体相关间擦疹型手足综合征。根据该病例合并腋臭手术史,手术部位皮肤正常,推测该病发病机制可能为药物经汗腺排泄到皮肤后诱发的皮肤毒性反应。     

In vivo protection against scorpion toxins by liposomal immunization

The possibility of raising a humoral immune response able to induce protection from the lethal effects of scorpion toxins was evaluated in the mouse model. A toxic fraction from the venom of the scorpion Tityus serrulatus was entrapped in sphingomyelin-cholesterol liposomes which yielded a conveniently detoxified immunogen. After three injections of this immunogen, all but three of a group of 18 mice developed an IgG response which was shown to be both specific and of good affinity for the toxic antigen. In vitro neutralization assays indicated that pre-incubation of a lethal dose of the toxic fraction with immune sera strongly diminished its toxicity. In vivo protection assays showed that mice with the highest levels of circulating anti-toxin antibodies could resist the challenge by double the normal LD₅₀ of the toxic fraction, which killed all control non-immune mice. The protection was, however, found to be limited both in its duration and its effectiveness against higher amounts of toxin.     

Coronary Vascular Bed Perfusion with a Polyethylene Glycol-Modified Hemoglobin-Encapsulated Liposome, Neo Red Cell, in Rats

Whether hemoglobin (Hb) encapsulated liposomes have vasoconstrictive activity remains controversial. We therefore examined the vascular activity of a liposome Hb, Neo red cell (NRC), in a simple in vitro model of Langendorff perfusion of the rat heart using Krebs-Henseleit (KH) solution as the perfusate. In the KH solution, NRC (Hb at 1 mg/ml), however, induced an immediate and abnormal increase in perfusion pressure. Histological examinations revealed that embolisms were the likely cause of this disturbance. Inorganic crystals formed by the mixing of NRC with the perfusate were a possible source of the embolisms. We found that the addition of bovine serum albumin to the perfusate was effective in avoiding embolic events. This protocol was used to compare the vasoconstrictive properties of unmodified bovine Hb and NRC. Unmodified bovine Hb (1 mg/ml) caused an increase in perfusion pressure and a decrease in the duration of bradykinin-induced relaxation. In contrast, NRC (Hb at 1 mg/ml) had no such vasoconstrictive effects. These results provide the first information regarding perfusion of the circulatory vascular bed by NRC and further evidence that the encapsulation of Hb into liposomes is an effective approach to modulate Hb-related vasoconstrictive activity.     

Formulation and characterization of azidothymidine-loaded liposomes

Entrapment efficiency (EE%) and in vitro stability of azidothymidine (AZT)-loaded hand-shaken multilamellar vesicles (MLVs), freeze and thaw vesicles (FATMLVs), and reverse phase evaporation vesicles (REVs) were compared. AZT entrapment in FATMLVs was further studied by varying initial lipid concentrations, drug concentration, and lipid composition. The results suggest that AZT entrapment is dependent on the aqueous volume entrapped within liposomes, and the interaction between the drug and liposomal bilayer may not be significant. Increasing the lipid concentration increases the liposomal entrapment of AZT but the encapsulation yield decreases above a lipid concentration of 30 μmol/mL. No significant difference was observed in EE% when the AZT concentration was varied from 5 to 20 mg/mL. The entrapment efficiency was highest (43.2%) for DSPC/CHOL/PS (molar ratio 6:3:3) vesicles but DSPC/CHOL/PS liposome formulations in a molar ratio of 4:3:3 or 4:5:1 and DSPC/CHOL/SA liposome formulations in a molar ratio of 4:5:1 were found to be more stable in vitro. In vitro drug release from liposomes was dependent on bilayer composition and the method of preparation.     

Photodynamic therapy of experimental tumours with Zn(II)-phthalocyanine and pulsed laser irradiation

The effectiveness of a pulsed dye laser (673 nm) for photodynamic therapy (PDT) of tumours in the presence of Zn(II)-phthalocyanine (ZnPc) was evaluated using Lewis lung carcinoma-bearing mice. The tumours were irradiated with different pulse energies (from 0.4 to 10 mJ) at a constant fluence of 0.6 J cm^–2 at 24 h after administration of 0.25 mg kg^–1 body weight liposome-incorporated ZnPc. Maximal PDT effect, as evaluated by changes in mean tumour diameter, animal survival time and histological evaluation of tumour necrosis, was observed after 3.0 mJ pulse energy irradiation which appears to yield a deeper light penetration and a more efficient sensitizer excitation when compared with lower or higher pulse energies. Electron microscopic analysis of photo-treated tumour indicates preferential damage to malignant tissue as compared to endothelial cells.     

无环鸟苷亲脂性前体药物脂质体的制备及体外抗病毒活性(英文)

本文通过将无环鸟苷(acyclovir,简称ACV)2’位羟基分别与月桂酰氯或棕榈酰氯进行酯化反应,制得亲脂性前体药物无环鸟苷月桂酸酯和无环鸟苷棕榈酸酯(分别简称为C_(12)-ACV和C_(16)-ACV),使脂质体包封率从ACV的29.9％提高到C_(12)-ACV的95.6％和C_(16)-ACV的97.1％;漏泄实验表明在4℃透析60h后,一半以上的ACV从脂质体中漏泄,而C_(12)-ACV和C_(16)-ACV的滞留率分别为70％和80％;体外抗疱疹病毒的试验中,在最低试验浓度0.044μmol/L时,ACV不显示抗病毒活性,而C_(16)-ACV脂质体抑制细胞病变率达75％,说明前体药物通过与脂质体脂膜的结合增加了药物的进入细胞能力,从而提高了ACV的抗病毒能力。     

Trifluralin liposomal formulations active against Leishmaniadonovani infections

The purpose of this study was to increase the therapeutic index of the antiparasitic drug, trifluralin (TFL), to allow its parenteral administration without the need of toxic solvents. This was achieved by incorporating TFL in liposomes with high loading capacity. These formulations were stable in freeze-dried form during at least one year and in frozen form during at least three months. Therapeutic activity, assessed on a visceral model of infection, showed that TFL liposomes reduced the number of parasites by up to one third or one half as compared to negative control and to free TFL, respectively.     

Liposome-Mediated calcium phosphate formation in metastable solutions

Summary The present study examined the effect of anionic liposomes on precipitate formation in supersaturated calcium phosphate solutions. The liposomes were prepared by dispersing 7∶2∶1 molar mixtures of phosphatidylcholine, dicetyl phosphate, and cholesterol in buffered aqueous solutions containing 0 or 50 mM inorganic phosphate (P₁). Unencapsulated P_I was removed by gel filtration. The liposomes were then suspended in reaction solutions containing 2.25 mM Ca²⁺ and either 0, 1.0, or 1.5 mM P₁. All experiments were carred out at 22°C, pH 7.4, and 240 mOsm. External solution Ca²⁺ and P_I losses were found to be appreciable only when the membranes of liposomes containing entrapped P_I were made permeable to Ca²⁺ with the addition to the suspension of the ionophore X-537A. The Ca²⁺ losses, moreover, were up to 3 times as great (1.5 vs 0.5 mM) when accompained by external P₁ losses than in P_I-free external solutions where Ca²⁺ alone was involved. Previous studies showed that in this latter situation, decline in external Ca²⁺ concentration was the result of precipitate formation in the aqueous interiors of the liposomes. The present findings suggest that when the external solution phase was metastable, the apparent coupling of large additional Ca²⁺ losses with intraliposomal precipitation was due to secondary precipitation brought about by the seeding action of intraliposomal crystals penetrating into the external solution. The results may explain in part the origin of extravesicular mineral deposits in matrix vesicle calcification.     

Liposomes with nifedipine and nifedipine-cyclodextrin complex: calorimetrical and plasma stability comparison

Inclusion complexes of nifedipine with 2-hydroxypropyl-ß-cyclodextrin (HPβCD) were formed by the spray- and freeze-drying methods. Nifedipine or its inclusion complexes (Nifedipine-CD complex I and II) were incorporated into liposomes prepared by the ethanol injection method. The highest entrapment value (77.7% of the starting material) was achieved for liposomes with N-CD complex II. The interaction of nifedipine with lipid bilayers was measured calorimetrically. DPPC liposomes mixed with nifedipine or N-CD complex II showed a slight shift of the transition temperature of DPPC towards lower temperatures compared to DPPC liposomes alone or mixed with HPßCD. However, with nifedipine, an additional transition peak was seen at lower temperatures in the second and all subsequent scans which could not be detected for the N-CD complex. Plasma stability studies showed that liposomes containing N-CD complex II are more stable than liposomes containing nifedipine. Encapsulation of drug-cyclodextrin complexes into liposomes can increase the entrapment of the lipophilic drug and reduce its release from the carrier.