Bufalin enhances the anti-proliferative effect of sorafenib on human hepatocellular carcinoma cells through downregulation of ERK

The purpose of this study was to investigate the effect of bufalin on the anti-proliferative activity of sorafenib in the human hepatocellular carcinoma (HCC) cell lines PLC/PRF/5 and Hep G-2 and to determine the relevant molecular mechanism. Concurrent treatment with sorafenib and bufalin at a fixed ratio (25:1) for 48 h resulted in synergistic growth inhibition in HCC cell lines as determined by CCK-8 cell viability assays. Exposure of both PLC/PRF/5 and Hep G-2 cells to this combination of sorafenib (6.25 μM) and bufalin (50 nM) resulted in noticeable increases in apoptotic cell death, as evidenced by the disruption of mitochondria, compared to treatment with either agent alone. Although both sorafenib (6.25 μM) and bufalin (250 nM) alone inhibited the phosphorylation of ERK, the reduction in pERK was more pronounced in the cells treated with a combination of bufalin (50 nM) and sorafenib (250 nM). Furthermore, the inhibitory effect of bufalin on pERK was blocked by the PI3kinase inhibitor LY294002, suggesting that the reduction in pERK induced by bufalin might be mediated by AKT in these two HCC cell lines. Taken together, the results of our study suggest that bufalin enhances the anti-cancer effects of sorafenib on PLC/PRF/5 and Hep G-2 by contributing to the downregulation of ERK.     

High-level expression of the <Emphasis Type="Italic">Penicillium notatum</Emphasis> glucose oxidase gene in <Emphasis Type="Italic">Pichia pastoris</Emphasis> using codon optimization

The glucose oxidase (GOD) gene from Penicillium notatum was expressed in Pichia pastoris. The 1,815 bp gene, god-w, encodes 604 amino acids. Recombinant GOD-w had optimal activity at 35–40°C and pH 6.2 and was stable, from pH 3 to 7 maintaining >75% maximum activity after incubation at 50°C for 1 h. GOD-w worked as well as commercial GODs to improve bread making. To achieve high-level expression of recombinant GOD in P. pastoris, 272 nucleotides involving 228 residues were mutated, consistent with the codon bias of P. pastoris. The optimized recombinant GOD-m yielded 615 U ml⁻¹ (2.5 g protein l⁻¹) in a 3 l fermentor—410% higher than GOD-w (148 U ml⁻¹), and thus is a low-cost alternative for the bread baking industry.     

Responses of phytoplankton diversity to physical disturbance under manual operation in a large reservoir, China

In aquatic ecosystems, physical disturbances have been suggested to be one of the main factors influencing phytoplankton structure and diversity. To elucidate whether large-scale artificial operation of a hydroelectric reservoir has potential impacts on phytoplankton diversity, the impact on phytoplankton biodiversity of physical disturbances under artificial operation from May 2007 to April 2008 in tributaries of the Three Gorges Reservoir (TGR), China, was analysed. Two disturbance parameters, i.e. the absolute incremental rates of discharge (R _d,i ) and precipitation (R _p,i ), were created in this study for evaluating physical disturbance intensities during low and high water level periods of the TGR. Results showed that river discharge seemed to be the main factor controlling the phytoplankton diversity in low water level periods (≤151 m), and that precipitation was a potential promoter of the physical disturbance. During the 156-m impoundment process, the species diversity clearly decreased due to the high dilution effect on the phytoplankton communities. At high water level periods (>151 m), the low levels of disturbance eventually allowed the phytoplankton community to approach competitive exclusion in late February 2008. Sharply declining diversity values appeared when the Dinophyta blooms occurred in late March and late April 2008 (Peridinium and Ceratium, respectively).     

Screening and characteristics of a butanol-tolerant strain and butanol production from enzymatic hydrolysate of NaOH-pretreated corn stover

As a gasoline substitute, butanol has advantages over traditional fuel ethanol in terms of energy density and hydroscopicity. However, solvent production appeared limited by butanol toxicity. The strain of Clostridium acetobutylicum was subjected to mutation by mutagen of N-methyl-N'-nitro-N-nitrosoguanidine for 0.5?h. Screening of mutants was done according to the individual resistance to butanol. A selected butanol-resistant mutant, strain 206, produced 50?% higher solvent concentrations than the wild-type strain when 60?g glucose/l was employed as substrate. The strain was also able to produce solvents of 23.47?g/l in 80?g/l glucose P2 medium after 70?h fermentation, including 5.41?g acetone/l, 15.05?g butanol/l and 3.02?g ethanol/l, resulting in an ABE yield and productivity of 0.32?g/g and 0.34?g/(l?h). Subsequently, Acetone-butanol-ethanol (ABE) production from enzymatic hydrolysate of NaOH-pretreated corn stover was investigated in this study. An ABE yield of 0.41 and a productivity of 0.21?g/(l?h) was obtained, compared to the yield of 0.33 and the productivity of 0.20?g/(l?h) in the control medium containing 52.47 mixed sugars. However, it is important to note that although strain 206 was able to utilize all the glucose rapidly in the hydrolysate, only 32.9?% xylose in the hydrolysate was used after fermentation stopped compared to 91.4?% xylose in the control medium. Strain 206 was shown to be a robust strain for ABE production from lignocellulosic materials and has a great potential for industrial application.     

高粱种质材料幼苗期耐盐碱性评价

采用Hoagland营养液砂培法,以NaCl和Na2CO3组成的混合盐碱对高粱幼苗进行胁迫处理,建立高粱幼苗期耐盐碱评价方法,并评价了66份高粱种质材料的耐盐碱性.结果表明:盐浓度在8.0～12.5 g·L-1时,高粱耐盐碱品种‘TS-185’与盐碱敏感品种‘Tx-622B’在幼苗期的耐盐碱性差异明显,表明进行高粱幼苗期耐盐碱性评价时适宜的盐浓度范围为8.0～12.5 g· L-1.在10.0和12.5 g·L-12个盐浓度下,66份高粱种质材料的相对存活率、相对地上部鲜质量和相对株高的差异均达显著水平,表明不同品种的耐盐碱性不同.其中,‘三尺三’为高度耐盐碱品种,‘MN-2735’等16个品种为耐盐碱品种,‘EARLY HONEY’等32个品种为中等耐盐碱品种,‘Tx-622B’等16个品种为盐碱敏感品种,‘MN-4588’为高度盐碱敏感品种.苏丹草类型高粱一般具有较高的耐盐碱性,而保持系对盐碱较为敏感.     

Human amniotic fluid-derived c-kit(+) and c-kit (-) stem cells: growth characteristics and some differentiation potential capacities comparison

Amniotic fluid (AF) contains heterogeneous and multipotential cell types. A pure mesenchymal stem cells group can be sorted from AF using flow cytometry. In order to evaluate a possible therapeutic application of these cells, the human AF-derived c-kit⁺ stem cells (c-kit⁺ AFS) were compared with the c-kit⁻ (unselected) stem cells (c-kit⁻ AFS). Our findings revealed that the optimal period to obtain c-kit⁺ AFS cells was between 16 and 22 weeks of gestation. Following cell sorting, c-kit⁺ AFS cells shared similar morphological and proliferative characteristics as the c-kit⁻ AFS cells. Both c-kit⁺ and c-kit⁻ AFS cells had the characteristics of mesenchymal stem cells through surface marker identification by flow cytometric and immunocytochemical analysis. Both c-kit⁺ and c-kit⁻ AFS cells could differentiate along adipogenic and osteogenic lineages. However, the myocardial differentiation capacity was enhanced in c-kit⁺ AFS cells by detecting GATA-4, cTnT, α-actin, Cx43 mRNA and protein expression after myocardial induction; whereas induced c-kit⁻ AFS cells were only detected with GATA-4 mRNA and protein expression. The c-kit⁺ AFS cells could have potential clinical application for myogenesis in cardiac regenerative therapy.     

Effects of Chronic Cadmium Poisoning on Zn, Cu, Fe, Ca, and Metallothionein in Liver and Kidney of Rats

An experiment was conducted to invest effects of chronic cadmium poisoning on Zn, Cu, Fe, Ca, and metallothionein gene expression and protein synthesis in liver and kidney in rats. Forty rats, 6?weeks old, were randomly allocated into two groups. A group was given CdCl(2) (1?mg/KgCd(2+)) by intraperitoneal injection once a day. The other group was treated with normal saline in the same way. Liver and kidney were collected for analysis at the end of the third week. Results showed that Cd exposure increased Cd (P?相似文献   

不同强度及时间窗骨骼肌缺血后处理对兔心肌的保护作用

目的:通过比较不同强度及时间窗骨骼肌缺血后处理对兔缺血/再灌注心肌的保护效能,试图寻找最佳强度和时间窗的骨骼肌缺血后处理方案。方法:健康新西兰大白兔42只(雄性)随机分为7组(n=6):①假手术组(Sham)、②缺血对照组(CON)、③标准骨骼肌后处理组(SP)、④延迟6min骨骼肌后处理组(6M-DSP)、⑤延迟1 min骨骼肌后处理组(1M-DSP)、⑥骨骼肌后处理加强组(SSP)、⑦骨骼肌后处理减弱组(WSP)。以开胸结扎冠状动脉左室支固定部位方法制作缺血/再灌注模型,以游离并夹闭双侧腹股沟髂外动脉固定位置方法造成骨骼肌缺血,再灌注末以TTC法确定心肌梗死范围,并分别于心肌缺血前、后及再灌注1 h、2 h,以生化法测定血清肌酸激酶(CK)及乳酸脱氢酶(LDH)水平。结果:和CON组相比,1M-DSP组心肌梗死重量比及面积比分别下降了42.32%及42.68%、SP组分别下降了49.97%及43.78%、SSP组分别下降了48.36%及48.86%,(P均<0.05),但三组之间相比,心梗范围未见明显差异;而6M-DSP、WSP组与CON组相比未见心肌保护作用;肌酸激酶(CK)的水平和梗死范围变化趋势一致。结论:兔在心肌缺血/再灌注之前完成骨骼肌5 min缺血/1 min再灌注1次循环的缺血后处理,可以起到明显的心肌保护作用。     

厄贝沙坦对人脐静脉内皮细胞株EA.hy926增殖、凋亡、VEGF mRNA表达的影响

目的:应用不同浓度厄贝沙坦对人脐静脉内皮细胞株EA.hy 926的增殖、凋亡生物学效应及血管发生主要基因VEGFmRNA的表达进行体外研究,探讨厄贝沙坦对内皮细胞的血管生成效应。方法:各种浓度厄贝沙坦对人脐静脉内皮细胞株EA.hy926共同孵育24 h。细胞增殖采用CCK8法分析,Annexin V/PI双染法检测细胞凋亡。RT-PCR验证VEGFmRNA的表达。结果:厄贝沙坦各浓度干预组细胞形态无明显变化,CCK8结果提示厄贝沙坦各干预组相比对照组细胞增殖活力增高(P<0.05),呈浓度非依赖性。流式细胞仪分析厄贝沙坦各浓度干预组细胞无明显凋亡。RT-PCR发现厄贝沙坦1×10-4,1×10-5,1×10-6mol/L浓度组VEGFmRNA表达增高(P<0.05)。结论:厄贝沙坦促进EA.hy926细胞株细胞增殖,上调VEGFmRNA的表达。这提示除了降压效应,血管紧张素受体拮抗剂在缺血性心脏病如慢性心力衰竭治疗中具有一定作用。     

5-羟甲基胞嘧啶的研究进展

CpG二核苷酸中胞嘧啶的甲基化形式5-甲基胞嘧啶(5-methylcytosine,5mC)在哺乳动物中是一种常见的表观遗传修饰,在基因表达调控、发育调节、基因组印迹等方面发挥重要作用。近3年来研究发现,除了5mC外,胞嘧啶碱基的另一种修饰—5-羟甲基胞嘧啶(5-hydroxymethylcytosine,5hmC)在哺乳动物的多种组织中有着丰富的表达,它可能与5mC有着不同的生物学功能。文章就近年来5hmC的研究进展进行了综述。