Cyanide and migratory birds at gold mines in Nevada,USA

Since the mid-1980s, cyanide in heap leach solutions and mill tailings ponds at gold mines in Nevada has killed a large but incompletely documented number of wildlife (>9,500 individuals, primarily migratory birds). This field investigation documents the availability of cyanide at a variety of typical Nevada gold mines during 1990 and 1991, describes wildlife reactions to cyanide solutions, and discusses procedures for eliminating wildlife loss from cyanide poisoning. Substantial progress has been made to reduce wildlife loss. About half of the mill tailings ponds (some up to 150 ha) in Nevada have been chemically treated to reduce cyanide concentrations (the number needing treatment is uncertain) and many of the smaller heap leach solution ponds and channels are now covered with netting to exclude birds and most mammals. The discovery of a cyanide gradient in mill tailings ponds (concentration usually 2–3 times higher at the inflow point than at reclaim point) provides new insight into wildlife responses (mortality) observed in different portions of the ponds. Finding dead birds on the tops of ore heaps and associated with solution puddling is a new problem, but management procedures for eliminating this source of mortality are available. A safe threshold concentration of cyanide to eliminate wildlife loss could not be determined from the field data and initial laboratory studies. New analytical methods may be required to assess further the wildlife hazard of cyanide in mining solutions.     

α-Smooth-muscle actin expression in normal and fibrotic human livers

To determine the significance of the expression of -smooth-muscle actin in the fibrotic human liver, normal and diseased livers were stained with anti--smooth-muscle-actin antibody by an immunoperoxidase method. Vitamin A-containing lipocytes were also identified by the modified Kupffer's gold chloride method. In the normal human liver, lipocytes as well as vascular smooth muscle cells expressed -smooth-muscle actin. In alcoholic liver disease, there was an increase in the cells positive for -smooth-muscle actin adjacent to the fibrotic areas, but the response of lipocytes to the gold chloride reaction diminished. In chronic hepatitis, the cells positive for -smooth-muscle actin increased around the enlarged portal areas, and the response to the gold chloride reaction did not change appreciably. An increase in the cells positive for -smooth-muscle actin was associated with the progression of hepatic fibrosis in the liver of patients with alcoholic liver disease and chronic hepatitis.     

Liposomes and Nanoparticles in the Treatment of Intracellular Bacterial Infections

The treatment of infections caused by obligate or facultative intracellular microorganisms is difficult because most of the available antibiotics have either poor intracellular diffusion and retention or reduced activity at the acidic pH of the lysosomes. The need for antibiotics with greater intracellular efficacy led to the development of endocytosable drug carriers, such as liposomes and nanoparticles, which mimic the entry path of the bacteria by penetrating the cells into phagosomes or lysosomes. This Review assesses the potential of liposomes and nanoparticles in the targeted antibiotic therapy of intracellular bacterial infections and diseases and the pharmaceutical advantages and limitations of these submicron delivery systems.     

聚甲基丙烯酸酯纳米粒作为反义寡核苷酸传递系统的研究聚甲基丙烯酸酯纳米粒作为反义寡核苷酸传递系统的研究

目的 研究聚甲基丙烯酸酯阳离子纳米粒作为反义寡核苷酸传递系统的可行性。方法 以Eudragit RL100和RS100为材料,采用溶剂-非溶剂法制备纳米粒,再与寡核苷酸混合即得载药纳米粒。用透射电镜观察其形态、粒径测定仪测定粒径、超滤法测定药物的包封率,通过台盼蓝拒染试验和红细胞溶血试验测定纳米粒的细胞毒性,用流式细胞仪测定荧光标记的寡核苷酸的入胞量。结果 纳米粒的形态规整、大小均匀,平均粒径为127 nm左右,几乎所有的药物被负载。使用聚甲基丙烯酸酯纳米粒作为反义寡核苷酸载体后,进入细胞内的药物量急剧增加,并有显著的剂量依赖性,但对细胞有轻微的毒性作用。结论 聚甲基丙烯酸酯阳离子纳米粒是一种稳定、高效的反义寡核苷酸传递系统。     

阿苯达唑聚氰基丙烯酸正丁酯纳米粒的制备、性质及其组织靶向性研究阿苯达唑聚氰基丙烯酸正丁酯纳米粒的制备、性质及其组织靶向性研究

目的制备阿苯达唑聚氰基丙烯酸正丁酯纳米粒（albendazole polybutycyanocrylate nanoparticles，ABZ-PBCA-NP）TDDS给药系统，并考察相关特性及组织分布靶向性。方法种子乳化聚合法制备阿苯达唑纳米粒；等温吸附法考察纳米粒载药特性；动态透析法研究4种制剂的体外释药动力学；同位素标记阿苯达唑纳米粒在小鼠脏器组织分布和生物利用度。结果ABZ-PBCA-NP体外释药遵循Higuchi方程，加入PVP制成的载药纳米粒符合双指数函数。纳米粒的载药方式遵循Langmuir吸附方程。小鼠ig ³H-ABZ-PBCA-NP后, 药物的肝、脾中的靶向指数分别为11.4和3.9，阿苯达唑纳米粒和混悬剂相对生物利用度分别为76.0%和36.9%。结论制备纳米粒加入PVP可使药物具吸附性和分散性，纳米粒载体可降低药物与血浆蛋白结合率，增强药物的肝、脾脏器靶向性和延缓释药。     

Cellular uptake and concentrations of tamoxifen upon administration in poly(ε-caprolactone) nanoparticles

Purpose: In an attempt to increase the local concentration of tamoxifen in estrogen receptor positive breast cancer cells, we have prepared and characterized poly (ε-caprolactone) (PCL) nanoparticle formulation. Methods: PCL (mol wt 14,800 daltons) nanoparticles were prepared by the solvent displacement method in acetonewater system in the presence of Pluronic F-68. PCL nanoparticles, labeled with rhodamine 123, were incubated with MCF-7 estrogen receptor positive breast cancer cells to determine uptake, intracellular distribution, and localization as a function of time. Intracellular drug concentrations over a specified period of time using different initial doses were examined using tritiated [³H]-tamoxifen. Results: A significant fraction of the administered rhodamine 123-loaded PCL nanoparticles was found in the perinuclear region of the MCF-7 cells, where estrogen receptors are also localized, after 1 hour of incubation. Measurements of the intracellular concentrations revealed that most of the administered nanoparticle dose was internalized within the first 30 minutes of incubation, and the uptake followed saturable transport kinetics. Conclusion: Results of this study show that PCL nanoparticles were rapidly internalized in MCF-7 cells and intracellular tamoxifen concentrations followed a saturable process. This approach may provide better therapeutic benefit by delivering the drug locally, near the tumor cells, for a longer period of time.     

雷公藤甲素聚乳酸纳米粒对大鼠睾丸组织的影响

目的　观察采用聚乳酸纳米粒能否减轻雷公藤甲素的大鼠睾丸毒性。方法　雄性Wistar大鼠分别ig 0 .2及 0 .6mg·kg- 1雷公藤甲素 (非纳米粒组 )及其聚乳酸纳米粒混悬液 (纳米粒组 ) ,连续给药 15d ,以ig生理盐水的大鼠为对照组 ,测定睾丸的脏器系数及其组织匀浆液中酸性磷酸酶 (ACP)活性和果糖含量 ,光镜观察睾丸组织的病理学变化。结果在 0 .6mg·kg- 1剂量下 ,非纳米粒组睾丸ACP活性和果糖的含量均明显低于纳米粒组 (P <0 .0 5 )。光镜观察显示 ,雷公藤甲素 0 .6mg·kg- 1可引起大鼠睾丸的损伤 ,非纳米粒组引起的病变程度明显重于纳米粒组 ,主要表现为睾丸萎缩 ,各级生精细胞变性、坏死、数量减少或消失 ,出现了多核巨细胞。结论以聚乳酸作为药物载体的纳米体系 ,可明显减轻雷公藤甲素对睾丸的毒性     

游离细胞甘露糖受体的亲和细胞化学电镜观察

目的 对小鼠腹腔巨噬细腻及人精子的甘露糖受体（ＭＲ）进行超微结构定位。方法 采用甘露糖基化牛血清白蛋白（ＤＭＡ）结合１０ｎｍ胶体金制备探针ＤＭＡ－Ｇ１０,以此探针标记小腹腔巨噬细胞和获能前后的人精子,并用疼爱 射电子显微民制备的ＤＭＡ－Ｇ１０具有基露糖基结合特性。小鼠腹腔巨噬细胞可分为明、暗中类型。“暗细胞”不含ＭＲ,“明细胞”细胞膜表面含ＭＲ,该受体与ＤＭＡ－Ｇ１０结合后内化入细胞内。人 子发生     

眼用环孢霉素A缓释超微粒的制备及眼内分布研究

目的探讨壳聚糖-胆固醇双亲性聚合物包载环孢霉素A的缓释性及超微粒制备及眼内分布.方法壳聚糖-胆固醇双亲性聚合物与环孢霉素A共溶于溶剂中,对水透析形成超微载药微粒,37℃条件下测试超微粒体外释放状态.以放射性99锝标记壳聚糖超微粒,制成滴眼剂,以SPECT测试超微粒在兔眼中的滞留时间.结果壳聚糖载药超微粒可在6小时内缓释环孢霉素A,超微粒在给药后4小时在眼表具有良好的滞留性.结论以壳聚糖双亲性聚合物包载环孢霉素A对干眼症的治疗具有潜在的应用价值.     

锑掺杂纳米二氧化锡颗粒在乙二醇中的分散稳定性

开发了二次球磨湿法制备锑掺杂纳米二氧化锡(ATO)/乙二醇(EG)稳定体系的新方法;选用硅烷偶联剂KH 570,实现了ATO颗粒在EG溶液中的均匀分散和稳定性控制;研究了分散工艺参数对体系的影响,探讨了ATO颗粒的表面包覆改性机理。研究表明:分散剂KH 570的含量和体系的pH显著影响ATO在EG中的分散稳定性,在KH 570含量为1.5%,体系pH为8.5时,ATO/EG浆料的分散性能最佳。KH 570与ATO颗粒表面羟基发生的化学键结合,提高了颗粒表面的疏水性,改善了ATO颗粒与有机极性溶剂及高聚物之间的亲和力。