Down-regulation of αGal epitopes by co-transfection of α1,3-galactosidase gene and α1,2–fucosyltransferase gene

The polycarbohydrate structure of Galα1- 3Ga1β1-4GluNAc-R （known as αGal epitopes of xenoantigen）, produced by α1-3-galactosyltransferase （α1,3-GT） in the course of animal development, is the major xenoantigen on the cell surface of porcine which causes hyperacute rejection in pig-to-human xenotransplantation. Alpha-1,3-galactosidase （AGL）, a hydrolytic enzyme, can remove the terminal α1,3-galactosyi from the Galα1-3Galβ1-4GluNAc-R structure resulting in cleaning αGai epitopes from the porcine cells. Aipha-1,2-fucosyitransferase （HT） can modify the surface carbohydrate phenotype of porcine cells, bringing about reduction of αGai epitopes expression. In this study, human AGL and HT gene were co-transfected to porcine fetal fibroblast （PFFb） in equimolar concentration to reduce the xenoantigen. Gene and protein of hAGL and HT were both detected to express at high level by RT-PCR and Western blot, respectively. There was an 84% reduction in αGai xenoantigen and an 82% increase in H antigen as assayed by flow cytometry in the AGL and HT gene co-transfected PFFb. The number and morphology of transgenic PFFb chromosome were normal. Findings indicate that Galα1-3Gal epitopes of PFFb could be down regulated by AGL and HT co-transfection without deleterious effects on the chromosomal profile of the transgenic ceil.     

1,3-二氮杂环并[1,2-c] -1,2,3-三唑的简便合成

以DMF为介质,90 ℃条件下,2,4,6-三叠氮基均三嗪2与杂环烯酮缩胺3反应,简洁、高效合成1,3-二氮杂环并[1,2-c]-1,2,3-三唑4.2,4,6-三叠氮基均三嗪2作为叠氮的高效载体,使反应在较温和条件下进行.该反应具有时间短、操作简便、产率高(89%~93%)等特点.     

Comparative study on the effect of integrin αvβ3 on secretion of matrix metalloproteinases in human normal and carcinoma trophoblasts

The invasion of cytotrophoblast cells into the maternal endometrium during embryonic implantation is very similar to the metastasis of carcinoma cells. However, the significant difference is that the former is a highly controlled process. In this report, the effects of integrin αvβ3 on the secretion of matrix metalloproteinase (MMP) were compared between normal cytotrophoblast cells and choriocarcinoma cells by RT-PCR, gelatin zymography and immunocytochemistry. The results reveal that both normal cytotrophoblast cells and choriocarcinoma cells can express integrin αvβ3. The secretion of MMPs in normal cytotrophoblast cells is up-regulated by anti-αvβ3 antibody, whereas, decreased in choriocarcinoma cells. It was suggested that αvβ3 can modulate the expression of MMPs in trophoblasts, and this action is carried out through distinct mechanisms in normal and carcinoma cytotrophoblast cells.     

Optimization of cultural conditions for thermostable β-1,3-1,4-glucanase production by Bacillus subtilis ZJF-IA5

The optimization of cultural conditions for β-glucanase production by Bacillus subtilis ZJF-1A5 was investigated in flask trials. Temperature had great effect on β-glucanasc production which maximized atoptimal temperature of 37℃ and decreased significantly when temperature was over 37℃ . Charge quantity affected β-glucanasc production significantly. Adding oxygen vector N-dodecanc or acetic ether benefited β-glucanasc production, but it depended on the concentration and charge quantity. The results of fractional factorialdesign showed that age and size of inoculum and shaking speed were the key factors affecting β-glueanase production and the cultivation time span to reach the highest β-glucanasc activity. The optimal cultural conditionsfor p-glucanase production obtained with CCD were as follows: inoculum age and size (16 h, 3.82% (v/v)),shaking speed 210 r/rain, charge quantity of 30 mL in 250 mL flask and initial pH 7.0, cultured at 37℃ for 50 h. Repeated experimental results accorded with those predicted by a second-order polynomial model. The amount of p-glucanase, a-amylase and neutral protease produced by B subtills ZJF-1A5 was associated partially with cell growth. Those three enzymes‘ activities increased following the cell growth and increased signifi-cantly when cells entered the stationary phase.     

Synthesis and anticonvulsant activity of 1-substituted benzyl-N-substituted-1,2,3-triazole-4-formamides

Substituted benzyl azids were synthesized through the reaction of substituted benzyl chloride and sodium azid，which subsequently underwent cyclization with ethyl propiolate and amidation to give thirteen 1-substituted benzyl-N-substituted-1,2,3-triazole-4-formamide derivatives (3a-3m). The structure of the synthesized compounds was confirmed by IR, H-NMR, MS and elemental analysis. Their anticonvulsant activity against maximal electrolshock (MES) induced seizure was tested and the result showed that all these compounds possess anticonvulsant activity in different degrees. Among those, the compounds containing chloro atoms on the phenyl ring were less potent in anticonvulsant activity, while introducing one or two fluorin atoms on benzyl system increased its activity. Furthermore, their activity decreased when there was substituent on the nitrogen atom of carboxamide, and the larger the substituent, the lower the activity.     

Cloning and functional analysis of chloroplast division gene NtFtsZ2-1 in Nicotiana tabacum

FtsZ protein plays an important role in the division of chloroplasts. With the finding and functional analysis of higher plant FtsZ proteins, people have deepened the understanding in the molecular mechanism of chloroplast division. Multiple ftsZ genes are diversified into two families in higher plants, ftsZ1 and ftsZ2. On the basis of the research on ftsZ1 family, we analyzed the function of NtFtsZ2-1 gene in Nicotiana tabacum. Microscopic analysis of the sense and antisense NtFtsZ2-1 transgenic tobacco plants revealed that the chloroplasts were abnormal in size and also in number when compared with wild-type tobacco chloroplasts. Our investigations confirmed that the NtFtsZ2-1 gene is involved in plant chloroplast division.     

Characterization of γ-Fe2O3 nanoparticles prepared by transfor- mation of α-FeOOH

γ-Fe2O3 nanoparticles were successfully synthesized by a chemically induced transformation of α-FeOOH.In this method,the precursor(α-FeOOH)was prepared by chemical precipitation,and then treated with a mixed FeCl2/NaOH solution to produce the nanoparticles.X-ray diffraction indicated that when the precursor was treated with FeCl2(0.22 mol/L)and NaOH(0.19 mol/L),pure γ-Fe2O3 nanoparticles were obtained.However,when the concentration of FeCl2 was<0.22 mol/L or the concentration of NaOH was<0.19 mol/L,α-FeOOH and γ-Fe2O3 phases co-existed in the nanoparticles.Transmission electron microscopy observations showed that in the samples with co-existing phases,the nanoparticles did not have identical morphologies.The pure γ-Fe2O3 nanoparticles were polygonal rather than spherical.The volume ratio of α-FeOOH and γ-Fe2O3 was estimated for the two-phase samples from magnetization data obtained from a vibrating sample magnetometer.This chemically induced transformation is novel,and could provide an effective route for the synthesis of other metal oxide nanocrystallites.     

Cleaner and convenient preparation of 3-（4,6-dimethoxy-pyrimidin-2-yloxy）-2-methyl-phenol

Environmental concerns have highlighted the need of cleaner technologies. A cleaner, convenient and selective technology has been developed for the preparation of 3-(4,6-dimethoxy-pyrimidin-2-yloxy)-2-methyl-phenol (DPMP) from 2-methyl-benzene-1,3-diol in water as solvent. The isolated yield of DPMP is up to 86% in good selectivity. The product structure was characterized by conventional methods, 1^H-NMR and MS. This technology belongs to the modern concept of environmentally friendly low wastes or non-wastes technology (LWNWT).     

2,2-二氯-1,3-苯并二氧口恶茂与伯醇及2-巯基乙醇的竞争性反应

以2,2-二氯-1,3-苯并二氧口恶茂与一系列以1:1摩尔比混合的伯醇与2-巯基乙醇的混合溶液反应,结果表明:丁醇、异丁醇比2-巯基乙醇的反应活性大,相应的生成氯代产物的转化率比2-巯基乙醇高;异戊醇、仲戊醇、辛醇的反应活性比2-巯基乙醇小,相应的生成氯代产物的转化率比2-巯基乙醇低。     

2,2-二氯-1,3-苯并二氧噁茂与某些伯醇的反应性研究

2 ,2 -二氯 - 1,3-苯并二氧口恶茂与伯醇反应生成邻苯二酚碳酸酯和相应的氯代烷 ,氯代烷的产率从 2 0 %～97% ,取决于反应的摩尔比。对可能影响反应的因素如温度和反应时间也进行了探讨 ,结果表明 ,温度对反应产率的影响不很明显。     

Microstructure and properties of Ag–Ti3SiC2 contact materials prepared by pressureless sintering

Ti₃SiC₂-reinforced Ag-matrix composites are expected to serve as electrical contacts. In this study, the wettability of Ag on a Ti₃SiC₂ substrate was measured by the sessile drop method. The Ag–Ti₃SiC₂ composites were prepared from Ag and Ti₃SiC₂ powder mixtures by pressureless sintering. The effects of compacting pressure (100–800 MPa), sintering temperature (850–950℃), and soaking time (0.5–2 h) on the microstructure and properties of the Ag–Ti₃SiC₂ composites were investigated. The experimental results indicated that Ti₃SiC₂ particulates were uniformly distributed in the Ag matrix, without reactions at the interfaces between the two phases. The prepared Ag–10wt%Ti₃SiC₂ had a relative density of 95% and an electrical resistivity of 2.76×10-3 mΩ·cm when compacted at 800 MPa and sintered at 950℃ for 1 h. The incorporation of Ti₃SiC₂ into Ag was found to improve its hardness without substantially compromising its electrical conductivity; this behavior was attributed to the combination of ceramic and metallic properties of the Ti₃SiC₂ reinforcement, suggesting its potential application in electrical contacts.     

6-氯咪唑并[1,2-b]哒嗪-3-甲腈的合成研究

6-氯咪唑并[1,2-b]哒嗪-3-甲腈是抗癌新药新型TGF-β R1抑制剂BMS-986260的关键中间体。以水合肼和马来酸酐为起始原料,在酸催化下发生缩合反应,再用三氯氧磷进行氯化,与氨水发生氨解反应,接着与N,N-二甲基甲酰胺二甲基缩醛进行亚胺化反应,最后与溴乙腈发生关环缩合共5步反应合成。总收率为69.4%,产品经高效液相色谱（HPLC）紫外检测（波长254 nm）纯度为98.3%。产物结构经 ¹H NMR、¹³C NMR 确证。与已有的文献方法相比较,报道的合成路线具有化学选择性好、成本低廉、操作简便、收率高、避免柱层析分离、适合工业化生产的特点。     

Separation and analysis of the soluble trimer of Aβ1-40 and its effects on the rise in intracellular calcium

Alzheimer’s disease (AD) is one of the progressive neurodegenerative diseases associated with protein conformational transition, generally known as protein conformational disorders[1]. The general characteriza- tions of AD are the intracellular fibrillar…