Enhancing effect of a sea cucumber Stichopus japonicus sulfated polysaccharide on neurosphere formation in vitro

Neural stem/progenitor cells (NSPCs) exhibit therapeutic potential in neuronal diseases. Previously, we reported that a sulfated polysaccharide (HS) from the sea cucumber Stichopus japonicus increased the proliferation of NSPCs. Since the formation of neurospheres is related with NSPCs proliferation, we investigated the mechanism leading to neurosphere formation with and without HS. The results showed that HS significantly promoted neurosphere formation in a dose-dependent manner at concentrations between 2 and 8 μg/ml. Cell cycle analysis showed that HS increased the percentage of cells in S phase by 2.8-fold, as compared with the control. On the other hand, we observed a significantly rapid aggregation of NSPCs, resulting in formation of neurospheres as early as 2 h after HS treatment. However, the aggregation was not caused by chemotactic migration of NSPCs, as evidenced by the transwell chamber assay. Furthermore, the effect of HS on NSPCs was similar to the tumor necrosis factor-α (TNF-α) that activated nuclear factor NF-κB. Thus, we demonstrated that HS was able to promote cell proliferation and aggregation of NSPCs which could lead to the formation of neurospheres, and suggested that HS can serve as an adjuvant for promoting proliferation of NSPCs and formation of neurospheres.     

New insights into the structure of hybrid κ-/μ-carrageenan and its alkaline conversion

Hybrid κ-/μ-carrageenan, water-extracted from Kappaphycus alvarezzi, was incubated with Pseudoalteromonas carrageenovora κ-carrageenase. The five most abundant hybrid κ-/μ-carrageenan oligosaccharides were purified and their structure was determined by NMR and mass spectrometry. Since the enzyme-resistant fraction was small, these five oligosaccharides were representative of the distribution of the μ-carrabiose moieties along the carrageenan chain. Three main distributions of μ-carrabiose were found: -μ-, -μ-μ- and -μ-μ-μ-. Interestingly, the chemical shifts of the anomeric proton and carbon were strongly influenced by the identity of the adjacent carrabiose, which explains the asymmetrical D6S-H1 NMR signal that we observed. Although μ-carrabiose chemical shifts are usually attributed to blocks of μ-carrabiose as expected in ideal μ-carrageenan, we demonstrate that they are in fact due to μ-carrabiose units positioned between κ-carrabiose units. Using NMR and chromatography to monitor the alkaline conversion of μ- to κ-carrabiose, we found that the μ-carrabiose distribution (-μ-, -μ-μ-, -μ-μ-μ-) did not influence the conversion rate.     

Κ-酪蛋白基因多态性与牛乳加工性能的关联

为比较不同κ-酪蛋白基因型牛乳在加工特性上的差异,采用流变仪等仪器检测不同基因型牛乳的流变性能、热稳定性、表面疏水性、抗氧化性及乳化性。研究结果表明这几种κ-酪蛋白基因型牛乳之间热稳定性、表面疏水性和抗氧化性没有显著差异,而κ-酪蛋白基因型AB和AA牛乳的流变性能显著好于AE和BE,且AE的乳化性能显著强于其它3种基因型的牛乳,这表明κ-酪蛋白基因多态性与乳品加工之间存在关联。     

Comparative effects of tocotrienol-rich fraction, α-tocopherol and α-tocopheryl acetate on inflammatory mediators and nuclear factor kappa B expression in mouse peritoneal macrophages

The effects of tocotrienol-rich fraction (TRF), α-tocopherol (T) and α-tocopheryl acetate (TA) on lipopolysaccharide (LPS)-induced inflammatory responses in mouse peritoneal macrophages were examined. Results showed that at 5–30 μg/ml, all test compounds plus 1 μg/ml LPS exhibited no cytotoxic effects on macrophage cells. Compared with T and TA, TRF showed the strongest anti-inflammatory activity as demonstrated by its potency in inhibiting the LPS-induced nitric oxide (NO), prostaglandin E₂ (PGE₂), and proinflammatory cytokine (TNF-α, IFN-γ, IL-1β and IL-6) production. At 10 μg/ml, it significantly blocked the LPS induction of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) expression, but has no effect on cyclooxygenase-1 (COX-1). Furthermore, TRF also showed a greater inhibition on the nuclear factor kappa B (NF-κB) expression than T and TA. These results suggest that TRF could be a better agent than T and TA for use in the prevention of chronic inflammatory diseases.     

高酰基结冷胶与κ-卡拉胶复配胶的质构特性研究

用抗压实验和全质构测试对高酰基结冷胶(HA)与κ-卡拉胶(CA)复配胶的凝胶强度、形变性以及硬度进行分析。研究了Ca2+、Mg2+、K+、Na+四种离子以及HA与CA的质量比对复配胶质构特性的影响。实验中,总胶浓度控制为1%(w/v),离子浓度为2～80mmol/L,HA和CA的质量比为25:75、50:50、75:25。结果表明,二价离子较一价离子作用效果显著,其中Ca2+效果最为显著,复配胶在HA:CA=75:25时有显著的协同作用,HA与CA的复配胶有着较强的形变性。     

Effect of Mineral Fortification on Textural and Oxidative Stability of Reduced-Fat Spreads

The aim of this research was to investigate the effect of mineral fortification on the textural and oxidative stability of reduced-fat spreads produced using κ-carrageenan. Model systems were prepared containing varying amounts of zinc, copper, and iron. The hardness of the spreads stored at 5°C and 25°C was assessed over time using a penetrometer (20° cone), and it was observed that samples were generally weaker compared to the controls. Samples containing the transition minerals iron and copper were very susceptible to oxidation, becoming rancid rapidly. Low levels of zinc addition, between 2–10% of the recommended daily allowance (RDA), led to spreads with acceptable oxidative stability and a textural profile comparable to the controls over the storage period examined.     

解偶联蛋白-2在软脂酸诱导的HepG2细胞胰岛素抵抗中的作用及其与核转录因子-κB的关系

目的探讨解偶联蛋白-2(Uncoupling protein-2,UCP-2)在软脂酸诱导的HepG2细胞胰岛素抵抗(Insulin-resistance,IR)中的作用及其与核转录因子-κB(Nuclearfactor-κB,NF-κB)的关系。方法将HepG2细胞分为正常对照组、软脂酸组(加0.25mmol/L软脂酸)、高胰岛素组(加100nmol/L胰岛素)、软脂酸+京尼平组(加0.25mmol/L软脂酸和10μmol/L京尼平),培养24h后,再用100nmol/L胰岛素刺激,分别于12h后测定培养液中葡萄糖、MDA、SOD、ALT、AST、GGT、TG的浓度;油红O染色法观察细胞的脂变情况;流式细胞术检测线粒体膜电位改变;30min后采用半定量RT-PCR及Westernblot法检测细胞IRS-2、UCP-2及NF-κB的表达水平。结果胰岛素作用12h后,细胞培养液中葡萄糖含量软脂酸组与高胰岛素组比较,差异无统计学意义(P>0.05)。培养液中葡萄糖含量、ALT、AST、MDA、GGT、TG的含量及UCP-2和NF-κB的表达水平,软脂酸组均较正常对照组和软脂酸+京尼平组显著升高(P<0.05),软脂酸+京尼平组与正常对照组比较差异无统计学意义(P>0.05)。线粒体膜电位、SOD和IRS-2的水平,软脂酸组显著低于正常对照组和软脂酸+京尼平组(P<0.05),软脂酸+京尼平组与正常对照组比较差异无统计学意义(P>0.05)。结论 UCP-2在软脂酸诱导的肝脏胰岛素抵抗中起着重要作用,其机制可能与NF-κB有关。     

Validation of three dimensional film cooling modeling on convex surface for gas turbine blade

In this study, three dimensional computational predictions on the film cooling performance of single row and simple cylinder on the convex surface have been studied and compared with corresponding experimental data reported in the literature to validate the model. This computational prediction serves as the baseline for future studies of optimization in determining the film cooling effectiveness. Realizable κ–? turbulent model has been employed and energy equation has been solved. Grid independence study has been fulfilled using two kinds of meshing approach for the plenum and the cooling holes. Results of grid independence study showed that fine meshed plenum and cylinders of tetrahedral grids case have provide a good agreement with the related experimental data. Study of temperature ratio between the coolant and mainstream hot gas T_c/T_g has been performed using four values of temperature ratios that are 0.5, 0.6, 0.7, and 0.8. In all of these tests the mainstream duct of the models was generated with multigrid hexahedral mesh. Based on the heat-mass transfer analogy, results of this study showed good agreement of the film cooling effectiveness and temperature distribution in comparison to the related experimental data. The case in which combination of both plenum and cylinders in one volume with tetrahedral fine mesh generation and temperature ratio of T_c/T_g = 0.6 was found to be in good agreement with the experimental data among all of the other models. Computational prediction results have found an agreement with the experimental data, thus the approach is verified.     

“Smart” TDDB algorithm for investigating degradation in high-κ gate dielectric stacks under constant voltage stress

A new “smart” algorithm with adaptive testing is developed for automatically monitoring gate dielectric degradation during CVS using SILC. In this approach, stress current is monitored with a sampling rate as fast as ∼2 ms/point while SILC data are collected based on stress current changes and/or time intervals. This automated test was applied to study degradation of nMOS transistors with TiN/HfO₂ gate stacks where changes in the SILC data correlate directly with transitions in the stress current. From this SILC data, the differential resistance can be extracted and used to monitor conductivity throughout the degradation phase until breakdown.     

Extension of Far UV spectroscopic ellipsometry studies of High-κ dielectric films to 130 nm

Next generation CMOS devices use a high-κ dielectric layer (HfO₂, HfSiO, HfSiON and La₂O₃) grown on thin interfacial silicon dioxide as the gate dielectric. The higher dielectric constant of the Hf oxide based film stack allows a decrease in equivalent oxide thickness (EOT). Because the high-κ film stack has a greater physical thickness than an electrically equivalent SiO₂ film, the tunneling current decreases. It is a critical metrology requirement to measure the thickness of silicon dioxide and high-κ film stacks. Spectroscopic ellipsometry (SE) in the far UV wavelength region can be used to differentiate the high-κ films from silicon dioxide. This is due to the non-zero nature of the imaginary part of the dielectric function (beyond 6 eV) in the far UV region for high-κ films. There has been some conjecture that optical studies should be extended beyond 150 nm further into the VUV. This study addresses these concerns through determination of the dielectric function down to 130 nm. We show the fitted dielectric function of hafnium silicates and lanthanum oxide down to 130 nm. X-ray reflectivity (XRR) measurements were also performed on the high-κ films to complement the thickness measurements performed with SE.