聚乙烯亚胺载基因纳米颗粒的制备及其相关特性的研究

目的 制备聚乙烯亚胺载基因纳米颗粒并研究其理化性质和体外转染活性.方法 通过自由基聚合法制备出聚乙烯亚胺空载纳米粒后,用绿色荧光蛋白(PEGFP-C1)质粒做报告基因,以静电吸附的方式将PEGFP-C1质粒DNA和聚乙烯亚胺结合形成聚乙烯亚胺裁基因纳米粒,用透射电镜观察其形态特征,激光粒度分析仪测定其粒度分布、表面电位(Zeta电位),MTT试验检测聚乙烯亚胺纳米载体HepG2和L-02的细胞毒作用,用体外基因转染实验评价纳米粒的转染活性,用流式细胞仪测定转粢效率.结果 聚乙烯亚胺与聚甲基丙烯酸甲酯形成表面带正电荷的纳米粒,呈单分散球形,平均粒径为102.62 nm,Zeta电位为+46.2 mV.当PEGFP-C1质粒DNA与纳米粒的N/P为3.2:1以上时,两者方可完全结合形成复合物.PEI纳米粒可携带质粒DNA进入COS7细胞,并突破吞噬小泡释放质粒于细胞质,最终质粒聚集于细胞核内进行表达.结论 聚乙烯亚胺纳米粒可以用作基因递送的非病毒栽体系统,值得进一步研究.     

Synthesis and evaluation of a water‐soluble polymer to reduce Ac‐225 daughter migration

The actinium decay chain has been promoted as an in vivo alpha generator for therapy, but migration of daughters from the primary conjugate has lead to increased toxicity away from the target organ. To reduce daughter migration, polyethylenimine (PEI) was used with a primary chelator and secondary chelators. The primary chelator, DOTA, was used to coordinate ²²⁵Actinium and secondary chelators‐acetate and DTPA, were added to the polymer for coordination of daughters formed by decay. The ²²⁵Actinium polymer derivatives containing secondary chelators were found to retain radioactive daughters better than the ²²⁵Actinium bond to the primary alone. The retention of ²¹³Bismuth and ²⁰⁹Thallium had the following order from highest retained to lowest DOTA‐PEI‐DTPA≈DOTA‐PEI‐CH₂OO‐ > DOTA‐PEI. The data suggests this polymer approach could be used to reduce daughter migration and has potential for development of actinium labeled radiopharmaceuticals. Copyright © 2007 John Wiley & Sons, Ltd.     

梅毒压电石英晶体免疫传感器的研制

分别用聚乙烯亚胺(PE I)和戊二醛(G lu)溶液在压电石英晶体银电极上固定梅毒抗体来检测不同浓度的标准抗原溶液。抗体在晶体表面固化后通过原子力显微镜(AFM)显示依然保持Y型分子结构。石英晶体的响应线性范围5×10-5~1.25×10-4g/mL,相关系数为0.9976,最佳响应pH值为7.5。在检测时通过和BSA相对照,传感器有良好的选择性。最后,又对传感器重复性作了一定探讨。     

裴正学教授治疗肾炎经验撷英

以具体验案为例,介绍裴正学教授治疗肾炎的经验:一为开鬼门,洁净府,适用于外感风邪,肺失通调之急性肾炎;二为健脾利湿,适用于脾虚不运,水湿内停之慢性肾炎;三为补肾温阳,适用于肾阳虚损,气不化水之慢性肾炎.     

Antidepressant-like effects of Tagetes lucida Cav. in the forced swimming test

Aim of the Study

Tagetes lucida (Asteraceae), has been referred in Mexican traditional medicine for the treatment of different central nervous system (CNS) diseases, mainly depression. Nevertheless, the available scientific information about this species is scarce and there are no reports related to its possible effect on the CNS. In this work, the antidepressant-like effect of extract of Tagetes lucida was evaluated in rats, as well as its potential adverse effects on male sexual behavior (MSB).

Materials and methods

Antidepressant activity was studied using forced swimming test (FST), motor activity in the open-field test and on MSB in sexually experienced male. The aqueous extract of Tagetes lucida in doses of 5, 10, 50, 100 and 200 mg/(kg day)⁻¹ were administered orally for 14 consecutive days and evaluated on day 14, 2 h after the last dose treatment. Fluoxetine (10 mg/(kg day)⁻¹, p.o.) was used as the control positive.

Results

The aqueous extract (10, 50, 100 mg/(kg day)⁻¹) significantly reduced immobility and increased swimming without affecting climbing behavior in the FST. These same doses were not able to modify neither the motor activity nor the MSB.

Conclusion

These data indicate that the extract of Tagetes lucida possesses antidepressant-like properties in rats.     

Identification of CD4+ and CD8+ T cell epitopes of woodchuck hepatitis virus core and surface antigens in BALB/c mice

A therapeutic vaccine against chronic hepatitis B virus (HBV) infection requires the development of a strong and multispecific Th1 cell immune response. Woodchucks chronically infected with the woodchuck hepatitis virus (WHV) closely resemble HBV infection and represent the best animal model for this hepadnavirus-induced disease. Using the BIMAS “HLA Peptide Binding Predictions” program, we have identified and further characterized novel H-2^d-restricted CD8+ epitopes within the WHV core (peptides C#12–21, C#18–32, C#19–27, C#61–69) and surface antigens (peptides preS2#10–18, preS2#27–35, S#76–84, S#133–140 and S#257–265), respectively. These peptides bind to H-2^d with high efficiency and upon immunization of mice with peptide and Freund's adjuvant they induce the development of IFN-γ producing T cells. More importantly, WHV core peptides C#19–27 and C#61–69 and WHV surface peptides S#133–140 and S#257–265 were also recognized by CD8+ T cells after immunization of mice with DNA/PEI nanoparticles. Direct stimulation of splenocytes obtained from such DNA-immunized mice with peptides C#18–32, S#76–84, and S#257–265 resulted in significant production of IFN-γ. Thus, we have identified T cell determinants in mice from WHV core and surface antigens that have important value for designing and evaluating an effective vaccine against hepadnavirus infection.     

Comparative in vivo study of poly(ethylene imine)/siRNA complexes for pulmonary delivery in mice

Pulmonary siRNA delivery offers a new way to treat various lung diseases. Poly(ethylene imines) (PEIs) are promising cationic nanocarriers and various modifications are still under investigations to improve their cytotoxicity and efficacy for siRNA delivery.In this study, we analyzed two different types of PEI-based nanocomplexes in mice after intratracheal administration regarding their toxicity and efficacy in the lungs. Ubiquitously enhanced green fluorescent protein (EGFP) expressing transgenic and BALB/c mice were intratracheally instilled with 35 μg siRNA complexed with the different types of PEI nanocarriers. Lung toxicity and inflammation were investigated after 24 h, 3 d and 7 d treatment and knockdown of EGFP expression was analyzed by flow cytometry and fluorescence microscopy five days post instillation.Three different polyplexes caused more than 60% knockdown of EGFP expression, but only the fatty acid modified low molecular weight PEI 8.3 kDa (C16-C18-EO25)1.4 specifically reduced EGFP expression in CD45+ leucocytes (25 ± 12%) and CD11b−/CD11c+ lung macrophages (36 ± 14%). Hydrophobic and hydrophilic PEG modifications on PEI caused severe inflammatory response and elevated levels of IgM in broncho-alveolar fluid (BALF). Thus, the PEG modification reduced cytotoxicity, but elevated the immune response and proinflammatory effects. Further investigations of the proinflammatory and immunomodulatory effects of the PEI-modified carriers are necessary to clarify the highly unspecific knockdown effects in the lung in more detail. Nevertheless, the more hydrophobic modification of PEI based non-viral vector system appeared to be a promising approach for improved siRNA therapeutics offering successful pulmonary siRNA delivery.     

Optimized dextran-polyethylenimine conjugates are efficient non-viral vectors with reduced cytotoxicity when used in serum containing environments

Polyethylenimine (PEI) is a cationic polymer that is an efficient transfection reagent marred by high toxicity and a susceptibility to aggregate in the presence of serum. Dextran is a biodegradable natural polysaccharide that can be used to reduce the toxicity of PEI and increase its stability in the presence of serum. In this study, small branched PEI units (800/2000 Da) were attached to dextran (Dex; 15/100-200 kDa) to form dextran-polyethylenimine (Dex-PEI) conjugates. The Dex-PEI conjugates were then tested as a gene carrier in the model HEK293 cell line. Dex-PEI conjugates displayed significantly lower cytotoxicity than PEI (25k). Both Dex-PEI and PEI efficiently delivered firefly luciferase encoded plasmid DNA (pDNA) to the HEK293 cells. Dex-PEI resulted in moderately lower transfection efficiencies than PEI 25k when the transfection was carried out in media without serum for 4h. However, in the presence of serum, which more accurately predicts the anticipated environment of non-viral vectors in vivo, Dex-PEI and unmodified PEI generated similar transfection efficiencies when incubated with the cells for 4h. When the incubation time of the vectors was increased to 48h, significantly higher transfection efficiencies were generated by Dex-PEI in comparison to PEI. Turbidity measurements showed that complexes formed between plasmid DNA and unmodified PEI were more susceptible to aggregation in serum-containing media than complexes formed from pDNA and Dex-PEI. Dex-PEI conjugates are therefore believed to have greater potential for translational applications because of lower cytotoxicity characteristics and improved stability in serum containing environments.     

Prospects for oral replicating adenovirus-vectored vaccines

Orally delivered replicating adenovirus (Ad) vaccines have been used for decades to prevent adenovirus serotype 4 and 7 respiratory illness in military recruits, demonstrating exemplary safety and high efficacy. That experience suggests that oral administration of live recombinant Ads (rAds) holds promise for immunization against other infectious diseases, including those that have been refractory to traditional vaccination methods. Live rAds can express intact antigens from free-standing transgenes during replication in infected cells. Alternatively, antigenic epitopes can be displayed on the rAd capsid itself, allowing presentation of the epitope to the immune system both prior to and during replication of the virus. Such capsid-display rAds offer a novel vaccine approach that could be used either independently of or in combination with transgene expression strategies to provide a new tool in the search for protection from infectious disease.     

Food Consumption and the Risk of Type 1 Diabetes in Children and Youth: A Population-Based,Case-Control Study in Prince Edward Island,Canada

Objective: The objective of this study was to determine if the consumption of certain foods during the year prior to diagnosis of type 1 diabetes mellitus (T1D) was associated with the risk of developing T1D in children and youth residing in Prince Edward Island, Canada.

Methods: Cases (n = 57) consisted of newly diagnosed patients with T1D during 2001 to 2004. Controls (n = 105) were randomly selected from the province's population, and matched to cases by age at diagnosis and sex. Food consumption in cases and controls was assessed using two previously validated food frequency questionnaires, and a survey was developed to collect information on potential environmental and genetic risk factors.

Results: The median age at diagnosis was nine years, and 67% of cases were male. After controlling for the matched variables and four significant environmental and genetic risk factors (family members with T1D, the number of infections during the first two years of life, place of residence, and father's education) in the final logistic regression model, the consumption of regular soft drinks (OR = 2.78, 95% CI = 1.21, 6.36) and eggs (OR = 2.50, 95% CI = 1.09, 5.75) were significant risk factors of T1D, when consumed once per week or more often.

Conclusion: Diet may play a role in the development of T1D. However, further research is needed to confirm these observed associations.