Effects of physicochemical characteristics of poly(2-(dimethylamino)ethyl methacrylate)-based polyplexes on cellular association and internalization

The cationic polymer poly(2-(dimethylamino)ethyl methacrylate) (p(DMAEMA)) is able to efficiently bind and condense DNA and to mediate transfection of a variety of cell types. In this study, fluorescence activated cell sorting (FACS), confocal laser fluorescence microscopy (CSLM) and electron microscopy (EM) techniques were used to investigate in vitro the cellular interaction of p(DMAEMA)-based polyplexes with human ovarian carcinoma cells (OVCAR-3). Cellular association and subsequent internalization only occurred when the polyplexes exhibited a positive zeta potential. Small-sized polyplexes have an advantage over large-sized complexes regarding cellular entry. The effect of the presence of tertiary amine groups versus the presence of quatenary amine groups was evaluated by comparing p(DMAEMA) with its quaternary ammonium analogue poly(2-(trimethylamino)ethyl methacrylate) (p(TMAEMA)). The combined cellular interaction and transfection results suggest that the latter polymer does not have an intrinsic endosomal escape property, in contrast to the 'proton sponge' effect proposed for p(DMAEMA). PEGylation of p(DMAEMA) effectively shielded the surface charge and yielded a notably lower degree of cellular interaction. Data on the effects of the presence of endocytosis inhibitors and an endosome-disruptive peptide in the culture medium on the cellular interaction and transfection activity of p(DMAEMA)-based polyplexes support endocytosis as being the principal pathway for intracellular delivery of plasmid. Both the CLSM and EM studies did not reveal the presence of polyplexes or plasmid outside the endocytic vesicles or within the nucleus, suggesting that intracellular trafficking from the endosomes to the nucleus is a very inefficient process.     

Assessment of new biocompatible Poly(N-(morpholino)ethyl methacrylate)-based copolymers by transfection of immortalized keratinocytes

Skin carcinomas are among the most commonly diagnosed tumors in the world. In this study, we investigated the transfection of immortalized keratinocytes, used as an in vitro model for skin carcinoma, using the antisense technology and poly(2-(dimethylamino)ethyl methacrylate) (PDMAEMA)-based copolymers. In order to improve the transfection efficiency of the classic PDMAEMA polymers, copolymers were synthesized including a poly(N-morpholino)ethylmethacrylate) (PMEMA) moiety for an improved proton-sponge effect, intended to favour the release of the oligonucleotide from the acidic endosome. These copolymers were synthesized either statistically (with alternating PDMAEMA and PMEMA fragments) or in blocks (one PDMAEMA block followed by one PMEMA block). MTT assays were performed using the PDMAEMA-PMEMA copolymers and revealed no significant cytotoxicity of these polymers at an N/P ratio of 7.3. Using fluorescent oligonucleotides and analyzing transfection efficiency by flow cytometry, we noticed no significant differences between the two kinds of copolymers. However copolymers with a higher DMAEMA content and a higher Mn were also those displaying the highest vectorization efficiency. Confocal microscopy showed that these copolymers induced a fine granular distribution of the transfected antisense oligonucleotides inside the cells. We also assessed the functionality of the transfected antisense oligonucleotide by transfecting immortalized GFP expressing keratinocytes with a GFP antisense oligonucleotide using these copolymers. A significant silencing was achieved with a PDMAEMA-PMEMA in block copolymer (Mn?=?41 000, 89 % PDMAEMA). Together, these results suggest that PDMAEMA-PMEMA copolymers combining low toxicity, vectorization and proton sponge properties, can be efficiently used to transfect immortalized keratinocytes and so open new perspectives in the therapy of skin carcinomas as well as of other skin diseases of genetic or immunological origin.     

2-(5-甲基-2-苯基-4-(口恶)唑)-乙醇的合成

以丙酰乙酸乙酯为起始原料,先溴化得到4-溴丙酰乙酸乙酯,再在甲苯中与苯甲酰胺回流环合得到2-(5-甲基-2-苯基-4-(口恶)唑)-乙酸乙酯,最后经氢化铝锂还原,得到目标杂环中间体2-(5-甲基-2-苯基-4-(口恶)唑)-乙醇.该合成方法反应步骤少,原料便宜,目标物的总收率为67.3%.     

LC-MS/MS法研究1-[1-(6-甲氧基-2-萘基)乙基]-2-(4-硝基苄基)-6,7-二甲氧基-1,2,3,4-四氢异喹啉氢溴酸盐在大鼠体内的代谢产物

采用液相色谱-串联质谱法对大鼠灌胃1-［1-(6-甲氧基-2-萘基)乙基］-2-(4-硝基苄基)-6,7-二甲氧基-1,2,3,4-四氢异喹啉氢溴酸盐(编号P91024)后粪便、尿液、胆汁和血浆中的主要代谢产物进行研究。通过比较给药样品和空白样品的全扫描总离子流色谱和选择离子扫描色谱图差别寻找I相代谢产物；根据其一级和二级质谱图，确定I相代谢产物的分子结构。完全提取I相代谢产物后的样品溶液，再用葡糖醛酸酶酶解，得II相结合物的苷元部分，采用与I相代谢产物鉴定同样方法寻找和鉴定II相代谢产物苷元的结构，进而确证II相代谢产物的分子结构。从大鼠粪便中鉴定出P91024的2个I相代谢物，从胆汁中鉴定出1个I相和5个II相代谢产物，从尿液中鉴定出1个I相和3个II相代谢产物，从血浆中鉴定出4个I相和1个II相代谢产物；并分别分析推测出它们的结构。P91024在大鼠体内被代谢转化为多种产物，利用LC-MS/MS可以快速寻找和鉴定。     

1-［1-(6-甲氧基-2-萘基)乙基］-2-(4-硝基苄基)-6,7-二甲氧基-1,2,3,4-四氢异喹啉氢溴酸盐的光降解产物研究

研究1-［1-(6-甲氧基-2-萘基)乙基］-2-(4-硝基苄基)-6,7-二甲氧基-1,2,3,4-四氢异喹啉氢溴酸盐(编号P91024)遇光后颜色变暗的光降解产物。采用HPLC-MS及波谱分析鉴定光降解产物的化学结构，并经有机反应合成对照验证。P91024光降解的3个主要产物分别为溴化N-(4-硝基苄基)-6,7-二甲氧基-3,4-二氢异喹啉、1-［1-(6-甲氧基-2-萘基)乙基］-6,7-二甲氧基-1,2,3,4-四氢异喹啉和2-异丙基-6-甲氧基萘。     

9-[2-(膦酰甲氧基)乙基]腺嘌呤一钠盐在比格犬体内的毒代动力学和毒理学研究

目的为9-[2-(膦酰甲氧基)乙基]腺嘌呤一钠盐(PMEA-Na)重复给药的毒性研究提供毒代动力学资料。方法采用液相色谱质谱联用方法测定样品中的药物浓度,数据经统计矩方法处理得到毒代动力学参数,并完成血清生化学及组织病理学检测。结果比格(Beagle)犬静脉单次及多次给药(14 d,每日1次)后,在给药剂量范围内, AUC均表现为剂量依赖性。在1.0, 3.0与6.0 mg·kg-1PMEA-Na时,AUC分别为(2.3±0.5),(8.4±1.6),(17.5±3.7)mg·L-1·h(单剂量)和(5.0±0.4),(15.9±3.2),(30.3±4.7) mg·L-1·h(多剂量)。PMEA-Na主要经肾脏排出体外,且给药14 d后肾功能受损药物排泄能力降低。与对照组比较, 6.0 mg·kg-1组血清生化学检测指标丙氨酸氨基转换酶、总胆红素、尿素氮、肌酐及甘油三酯均升高,葡萄糖水平下降。6.0 mg·kg-1组的组织病理学检查发现肝脏和肾脏有明显的病理形态学改变。结论比格犬经静脉多次给PMEA-Na 14 d后出现毒性反应,毒性靶器官主要为肾脏和肝脏。     

9-［2-(膦酰甲氧基)乙基］腺嘌呤一钠盐在比格犬体内的毒代动力学和毒理学研究

目的 为9-［2-(膦酰甲氧基)乙基］腺嘌呤一钠盐（PMEA-Na）重复给药的毒性研究提供毒代动力学资料。方法 采用液相色谱质谱联用方法测定样品中的药物浓度，数据经统计矩方法处理得到毒代动力学参数，并完成血清生化学及组织病理学检测。结果 比格(Beagle)犬静脉单次及多次给药（14 d，每日1次）后，在给药剂量范围内，AUC均表现为剂量依赖性。在1.0, 3.0 与6.0 mg·kg^-1 PMEA-Na时，AUC分别为（2.3±0.5），（8.4±1.6），（17.5±3.7）mg·L^-1·h(单剂量)和（5.0±0.4），（15.9±3.2），(30.3±4.7) mg·L^-1·h（多剂量）。PMEA-Na主要经肾脏排出体外，且给药14 d后肾功能受损药物排泄能力降低。与对照组比较, 6.0 mg·kg^-1组血清生化学检测指标丙氨酸氨基转换酶、总胆红素、尿素氮、肌酐及甘油三酯均升高, 葡萄糖水平下降。6.0 mg·kg^-1组的组织病理学检查发现肝脏和肾脏有明显的病理形态学改变。结论 比格犬经静脉多次给PMEA-Na 14 d后出现毒性反应，毒性靶器官主要为肾脏和肝脏。     

(2R,4R)-4-甲基-2-哌啶甲酸乙酯的合成工艺改进

目的 优化(2R,4R)-4-甲基-2-哌啶甲酸乙酯的合成工艺.方法 以S-(-)-α-甲基苄胺为原料,与乙醛酸乙酯反应得到[(S)-1-苯乙基亚胺基]乙酸乙酯,与异戊二烯进行环合后,再经不对称氢化和脱保护反应制得(2R,4R)-4-甲基-2-哌啶甲酸乙酯.结果 总收率从17.0％提高至47.6％.结论 本工艺可有效地降低生产成本.     

2-(3-氰基-4-羟基)苯基-4-甲基-5-噻唑甲酸乙酯的合成

目的优化非布司他关键中间体2-(3-氰基-4-羟基)苯基-4-甲基-5-噻唑甲酸乙酯(4)的合成方法。方法采用"一勺烩"方法,以4-羟基苯甲腈为起始原料,首先与硫氢化钠和无水氯化镁在N,N-二甲基甲酰胺中反应,所得中间体不经分离,直接加入2-氯乙酰乙酸乙酯进行环合反应,得到2-(4-羟基)苯基-4-甲基-5-噻唑甲酸乙酯(2);然后通过六亚甲基四胺/三氟乙酸进行Duff反应,得到2-(3-甲酰基-4-羟基)苯基-4-甲基-5-噻唑甲酸乙酯(3);再经盐酸羟胺/甲酸/甲酸钠体系脱水得到目标化合物。结果经四步反应合成非布司他关键中间体4,总收率为22.6%,其结构经核磁共振氢谱、质谱确证。结论改进后的工艺终产品无需柱色谱纯化,适合工业化生产。     

The fate of poly(2-dimethyl amino ethyl)methacrylate-based polyplexes after intravenous administration

Poly(2-dimethyl amino ethyl) methacrylate (pDMAEMA) cationic polymers have been shown to be efficient vectors for gene delivery in vitro. This contribution deals with the in vivo properties of polyplexes based on this polymer. In mice, pDMAEMA/[32P]-pLuc complexes distributed primarily to the lungs. The gene expression profile matched the biodistribution profile. In vitro turbidity experiments in serum showed severe aggregation upon addition of cationic polyplexes, pointing out the involvement of aggregates in the dominant lung uptake of the positively charged polyplexes. Incubations of polyplexes with albumin yielded a decline of the zeta potential of the complexes to negative values, making an electrostatic mechanism in the dominant lung uptake less likely. Hemagglutination experiments showed that the polyplexes induce the formation of extremely large structures when incubated with washed erythrocytes. Altogether, the present data indicate that aggregate formation and trapping of the formed aggregates in the lung capillary bed is probably responsible for the dominant lung uptake and transfection. Poly(ethylene)glycol (PEG) of the polymeric structures prevented the increase in the observed turbidity in serum seen with polyplexes and was also able to reduce interactions with erythrocytes. Currently, the in vivo fate of the PEGylated polyplexes is under investigation.     

Freeze-Drying of Poly((2-dimethylamino)ethyl Methacrylate)-Based Gene Delivery Systems

Pharmaceutical Research -     

The interaction of 1-(2(diarylmethoxy)ethyl)aziridines with histamine receptors in the longitudinal muscle strip of the guinea pig ileum.

The time course of the onset and decline of histamine antagonism by 1-(2-(diarylmethoxy)ethyl)aziridines, compounds which could be expected to have H1-receptor alkylating properties, was investigated on the longitudinal muscle strip of the guinea pig ileum. Experiments were performed with normal preparations and with muscle strips pretreated with a prostaglandin synthesis inhibitor in order to prevent spontaneous rise of muscle tone. In contrast to the previously reported observation that antihistaminic potency decreased with prolongation of the preincubation time, histamine antagonism by the aziridine compounds remained at a constant level for more than 60 min in the presence of indomethacin. This indicated that the aziridines are not hydrolyzed either directly in solution or after interaction with the tissue since the supposed hydrolysis product had a significantly lower antihistaminic activity. A comparison between 1-(2-diphenylmethoxy)ethyl)aziridine and diphenhydramine showed the former compound to have a slightly more rapid onset and a considerably more rapid decline of histamine receptor blockade. It was concluded that 1-(2-(diarylmethoxy)ethyl)aziridines did not alkylate the histamine H1-receptor in the longitudinal muscle layer of the guinea pig ileum.     

D2 dopaminergic and 5-HT1A serotonergic activity of 2-(1-naphthyl)ethyl- and 2-(2-naphthyl)ethyl amines

Several tertiary 2-phenylethyl, 2-(1-naphthyl)ethyl and 2-(2-naphthyl)ethyl amines were synthesized and their binding affinities for dopamine D(1), D(2) and serotonin 5-HT(1A) receptors evaluated in radioligand binding assays. All compounds were inactive in D(1) dopamine radioligand binding assay. The 2-(1-naphthyl)ethyl analogues expressed a low but significant binding affinity for the D(2) and moderate one for the 5-HT(1A) receptor subtypes. Most of the remaining compounds expressed binding affinity at the 5-HT(1A) receptor subtype but were inactive in D(2) receptor binding assay. Based on these results and considering the chemical characteristics of the compounds synthesized and evaluated for dopaminergic and serotonergic activity throughout the present study it can be concluded that hydrophobic type of interaction (stacking or edge-to-face) plays a significant role in the formation of receptor-ligand complexes of 2-(1-naphthyl)ethyl amines. This structural motive can be applied to design and synthesize new, more potent dopaminergic/serotonergic ligands by slight chemical modifications.     

One-step preparation of amino-PEG modified poly(methyl methacrylate) microchips for electrophoretic separation of biomolecules

A simple method for a chemical surface modification of poly(methyl methacrylate) (PMMA) microchips with amino-poly(ethyleneglycol) (PEG–NH₂) by nucleophilic addition–elimination reaction was developed to improve the separation efficiency and analytical reproducibility in a microchip electrophoresis (MCE) analysis of biomolecules such as proteins and enantiomers. In our procedure, the PEG chains were robustly immobilized only by introducing an aqueous solution of PEG–NH₂ into the PMMA microchannel. The electroosmotic mobilities on the modified chips remained almost constant during 35 days with 37 runs without any recoating. The PEG–NH₂ modified chip provided a fast, reproducible, efficient MCE separation of proteins with a wide variety of isoelectric points within 15 s. Furthermore, the application of the modified chip to affinity electrophoresis using bovine serum albumin gave a good chiral separation of amino acids.     

Clonazepam release from core-shell type nanoparticles of poly(-caprolactone)/poly(ethylene glycol)/poly(-caprolactone) triblock copolymers

The triblock copolymer based on poly(-caprolactone) (PCL) as hydrophobic part and poly(ethylene glycol) (PEG) as hydrophilic one was synthesized and characterized. Core-shell type nanoparticles of poly(-caprolactone)/poly(ethylene glycol)/poly(-caprolactone) (CEC) block copolymer were prepared by a dialysis technique. According to the amphiphilic characters, CEC block copolymer can self-associate at certain concentration and their critical association concentration (CAC) was determined by fluorescence probe technique. CAC value of the CEC-2 block copolymer was evaluated as 0.0030 g/l. CAC values of CEC block copolymer decreased with the increase of PCL chain length, i.e. the shorter the PCL chain length, the higher the CAC values. From the observation of transmission electron microscopy (TEM), the morphologies of CEC-2 core-shell type nanoparticles were spherical shapes. Particle size of CEC-2 nanoparticles was 32.3±17.3 nm as a monomodal and narrow distribution. Particle size, drug loading, and drug release rate of CEC-2 nanoparticles were changed by the initial solvents and the molecular weight of CEC. The degradation behavior of CEC-2 nanoparticles was observed by ¹H NMR spectroscopy. It was suggested that clonazepam (CNZ) release kinetics were dominantly governed by diffusion mechanism.     

Long Term Stability of Poly((2-dimethylamino)ethyl Methacrylate)-Based Gene Delivery Systems

Purpose. To study the stability of polymer-plasmid complexes (polyplexes) both as an aqueous dispersion and in their lyophilized form. Methods. The characteristics of the polyplexes (size, charge and transfection potential) were monitored at different temperatures. Moreover, we studied possible changes in the secondary and tertiary structure of the plasmid by agarose gel electrophoresis and by CD spectroscopy to gain insight into the mechanism of polyplex degradation. Results. The polyplexes preserved almost their full transfection potential after aging in an aqueous solution of 20 mM Hepes (pH 7.4) containing 10% sucrose at 4 and 20°C for 10 months. On the other hand, the polyplexes aged at 40°C were rather unstable and lost their transfection capability with a half-life of around 2 months. During storage, conformational changes in the secondary and tertiary structure of DNA were observed. When naked plasmid DNA was aged at 40°C as an aqueous solution and complexed with polymer just before the transfection experiment, a slower drop in its transfection capability was observed. The freeze-dried polyplexes using sucrose as lyoprotectant almost fully retained their transfection efficiency, even when aged at 40°C for 10 months. Conclusions. This study provides information about polyplex stability in aqueous dispersions on storage and demonstrates that freeze-drying is an excellent method to ensure long term stability.     

Alterations in human red blood cell properties induced by 3-(dimethylamino)phenol (in vitro)

3-(Dimethylamino)phenol (3-DMAP) exists in the environment as a transformation product of ureic herbicides and may also be considered as a derivative of phenoxyherbicides.

In this study, the activity of glutathione peroxidase, catalase and superoxide dismutase, as well as the level of free radicals and changes in cell morphology were measured in human erythrocytes exposed (in vitro) to 3-(dimethylamino)phenol. Human erythrocytes were incubated for 1 h in 3-DMAP at concentrations of 10–500 μg per 1 ml erythrocytes of 5% haematocrit.

The results show that 3-(dimethylamino)phenol increased the level of free radicals and changed the activity of glutathione peroxidase, catalase, superoxide dismutase and acetylcholinesterase. It also changed cell morphology.

All these results corroborated the thesis that 3-DMAP induces oxidative stress in cells. 3-DMAP changed the properties of the cell membrane, caused strong oxidation of haemoglobin, inhibited the levels of enzymatic and non-enzymatic antioxidants, which, in result, lead to generation of free radicals (ROS and semiquinones) that occurred in the exposed cells, predisposing them to oxidative damage.     

2-(2-氨基-4-噻唑)-(Z)-2-羟亚胺基乙酸乙酯的合成

以乙酰乙酸乙酯为原料，经溴化、肟化、环合，制得２ （２ 氨基 ４ 噻唑） （Ｚ） ２ 羟亚胺基乙酸乙酯，各步反应中间体无需分离纯化，操作简单，总收率４５％．     

Brain uptake and CNS levels of 1-(2-chloroethyl)-1-nitroso-3-(2-hydroxyethyl)urea (HECNU)

The uptake of ¹⁴C-labeled 1-(2-chloroethyl)-1-nitroso-3-(2-hydroxyethyl) urea (HECNU) into the brain was investigated in the rat after intracarotid injection according to the method of OLDENDORF, as well as in cisternal cerebrospinal fluid obtained by suboccipital puncture after i.v. injection of the drug.The brain uptake index was 31.9 ± 2.9%. Cerebrospinal fluid/blood quotients after i.v. injection were 0.82 at 10 min and 1.10 at 60 min. The results of both methods clearly show that HECNU, in spite of its hydrophilic property, easily penetrates the blood-brain barrier.     

The production of skeletal muscle atrophy and mammary tumors in rats by feeding 2-(2-furyl)-3-(5-nitro-2-furyl)acrylamide

Chronic toxicity and carcinogenicity of a food additive, 2-(2-furyl)-3-(5-nitro-2-furyl)acrylamide (AF-2) was examined by its oral administration to Wistar rats for 18 months. Male rats given 0.4% AF-2 diet developed ataxia of the hind foot around 4 months of feeding, and severe atrophy of skeletal muscles of the whole body was seen in 31 of 43 rats after 12 months. In female rats, mammary tumors developed in 78% of the animals given 0.4% AF-2 diet. Multiple papillomas were observed in the forestomach.