Saffron (Crocus sativus L.) increases glucose uptake and insulin sensitivity in muscle cells via multipathway mechanisms

Saffron (Crocus sativus Linn.) has been an important subject of research in the past two decades because of its various biological properties, including anti-cancer, anti-inflammatory, and anti-atherosclerotic activities. On the other hand, the molecular bases of its actions have been scarcely understood. Here, we elucidated the mechanism of the hypoglycemic actions of saffron through investigating its signaling pathways associated with glucose metabolism in C₂C₁₂ skeletal muscle cells. Saffron strongly enhanced glucose uptake and the phosphorylation of AMPK (AMP-activated protein kinase)/ACC (acetyl-CoA carboxylase) and MAPKs (mitogen-activated protein kinases), but not PI 3-kinase (Phosphatidylinositol 3-kinase)/Akt. Interestingly, the co-treatment of saffron and insulin further improved the insulin sensitivity via both insulin-independent (AMPK/ACC and MAPKs) and insulin-dependent (PI 3-kinase/Akt and mTOR) pathways. It also suggested that there is a crosstalk between the two signaling pathways of glucose metabolism in skeletal muscle cells. These results could be confirmed from the findings of GLUT4 translocation. Taken together, AMPK plays a major role in the effects of saffron on glucose uptake and insulin sensitivity in skeletal muscle cells. Our study provides important insights for the possible mechanism of action of saffron and its potential as a therapeutic agent in diabetic patients.     

超高压技术对低盐肉制品降盐机制及品质改良的研究进展

低盐肉制品的开发是当前肉类食品的发展趋势,但降低钠盐的添加量会引起肉品品质的劣变。超高压技术作为一种新型的非热加工技术,可以降低肉制品中的食盐使用量,改善肌肉蛋白质的功能特性,改进低盐肉制品的品质。本文从高压处理对低盐肉制品保水性、蒸煮损失、咸味、颜色以及微生物安全性5 个方面出发,综述了超高压技术在低盐肉制品品质改良应用中的研究进展,并在此基础上论述了超高压技术对低盐肉制品的降盐机制,指出该技术在低盐肉制品应用中存在的局限性,并对其未来的发展前景进行展望,以期为超高压技术在低盐肉制品中的应用和推广提供理论参考。     

不同月龄羊肉原料肉品质与涮食羊肉品质的关系

以6、12、18、24月龄的舍饲巴寒杂交羊为研究对象,每个月龄选择10头胴体质量相近的肉羊(公母各半)进行屠宰,采集后腿肉分析其理化特性、肌纤维特性、涮制出品率与涮食羊肉食用品质。结果表明:除了p H_(24)值、涮食羊肉弹性与涮制出品率外,不同月龄巴寒杂交羊后腿肉理化特性、肌纤维特性、涮食羊肉剪切力和质构、感官评价指标均存在显著差异(P0.05);咀嚼性、硬度与肌节长度呈显著正相关,相关系数为0.618和0.639;弹性与肌纤维密度呈显著正相关,相关系数为0.588;胶原蛋白含量与涮制出品率呈显著负相关,相关系数为-0.458;6月龄羔羊肉感官评价指标色泽、嫩度、风味以及总体可接受性得分均显著优于24月龄(P0.05),羔羊涮食羊肉片更受感官评价人员的喜爱。研究证实低月龄羔羊肉更适宜涮制食用。     

干酪乳杆菌6033蛋白酶降解肌肉蛋白质的作用研究

本试验将干酪乳杆菌(Lactobacillus casei，Lc)6033蛋白酶液按5％的比例分别加入肌浆蛋白和肌原纤维蛋白提取液，然后设定不同的pH值，于15℃培养7d，定时取样，测定反应后的pH值、十二烷基硫酸钠-聚丙烯酰胺凝胶电泳(SDS-PAGE)检测蛋白质的变化。结果发现：不同设定的肌浆蛋白和肌原纤维蛋白试验组在反应初期pH值均稍稍降低，随着反应进程，各试验组的pH值呈现出逐步升高的趋势；其中，肌浆蛋白以pH5．0、4．5组的变化较为明显，肌原纤维蛋白则以pH6．0、5．0、4．5组的变化较为明显。经7d振荡培养后，电泳检测发现，各试验组肌浆蛋白均表现出分解现象，尤其以pH5．0组和pH4．5组更为明显；而肌原纤维蛋白也都表现出了明显的分解现象，尤以pH5．0组肌原纤维蛋白分解最明显。     

矢车菊素-3-葡萄糖苷对骨骼肌细胞脂蛋白脂肪酶活性的影响

富含矢车菊素-3-葡萄糖苷(Cy-3-g)的花色苷提取物可抑制肥胖,但其作用机制不明。骨骼肌细胞脂蛋白脂肪酶(LPL)活性与肥胖相关,LPL使骨骼肌中的β-脂肪酸氧化增强,从而加速清除体内循环的甘油三酯(TG),抑制TG流向脂肪组织积聚而导致肥胖。本实验建立稳定的骨骼肌细胞分离培养方法,通过花色苷Cy-3-g干预骨骼肌细胞,研究Cy-3-g对细胞LPL活性的影响及其作用机制。结果表明：Cy-3-g通过激活一磷酸腺苷激活的蛋白激酶(AMPK)上调骨骼肌细胞LPL活性,提示Cy-3-g具有潜在的调节机体脂代谢作用,与含Cy-3-g的花色苷提取物的肥胖抑制作用密切相关。     

抑制昆虫飞行过程的农药作用靶标研究

新型靶标及其先导化合物的发现是创新农药研发的关键。通过分析GenBank数据库中海藻糖酶的序列信息和PDB中脂蛋白的三维结构,结合近年来对海藻糖水解酶类抑制剂的报道,分别探讨了海藻糖合成酶和水解酶、携脂蛋白apoLp Ⅲ以及脂质运载蛋白FABPs等作为农药作用靶标的可能性,为新型农药的研发提供了一定的理论依据。     

Efficient Gene Transfection into Mammalian Cells Mediated by Cross-linked Polyethylenimine

25 kDa branched polyethylenimine (PEI) has successfully been used for in vitro and in vivo gene delivery approaches, but it is cytotoxic. Smaller PEIs are usually non-cytotoxic but less efficient. In order to enhance the gene delivery efficiency and minimize cytotoxicity of PEI, we explored to synthesize cross-linked PEIs with degradable bonds by reacting amines of small branched 2000 Da PEI with small diacrylate (1,4-butanediol diacrylate or ethyleneglycol dimethacrylate) for 2–6 hours. The efficiency of the cross-linked PEIs during in vitro delivering plasmid containing enhanced green fluorescent protein (EGFP) gene reporter and their cytotoxicity were assessed in melanoma B16F10 cell and other cell lines. In vivo gene delivery efficiency was evaluated by direct injection delivery of the EGFP plasmid/cross-linked PEI complexes into mice and by estimating the EGFP expression in animal muscles. Compared to commercially available 25-kDa branched PEI, the cross-linked PEIs reported here could mediate more efficient expression of reporter gene than the 25-kDa PEI control, 19-fold more efficiently in B16F10 cells, 17-fold in 293T cells, 2.3-fold in 3T3 cells, and they exhibited essentially nontoxic at their optimized condition for gene delivery. Furthermore the transfection activity of polyplexs was preserved in the presence of serum proteins. The muscle transfected with the cross-linked PEI prepared here exhibited normal morphology and excellent gene expression. The cross-linked PEIs reported here were evidently more efficient than the commercial 25-kD PEI control and had less cytotoxicity in gene delivery in vitro and in vivo.     

带有迟滞非线性的气动运动模拟平台自抗扰轨迹跟踪控制

针对带有迟滞非线性的气动运动模拟平台的轨迹跟踪提出了带有切换扩张状态观测器的自抗扰控制方法。气动运动模拟平台的迟滞非线性特性主要指气动人工肌肉在正向充气反向放气时长度和拉力曲线的差异。针对此特性设计了切换扩张状态观测器来估计和补偿模型非线性,分别对于气动人工肌肉正反向充放气的不同模型采用不同的观测器增益,以提高状态估计效果,减小跟踪误差。进一步,设计了状态误差反馈控制器,得到了基于切换扩张状态观测器的二阶非线性动态系统全局有界稳定的充分条件。最后实验结果证实了所设计的切换扩张状态观测器的实际效果。     

高速开关阀驱动的气动肌肉关节的滑模变结构跟踪控制

建立了PWM高速开关阀控制的气动人工肌肉单关节的4阶SISO动态数学模型，针对实现轨迹跟踪目标，采用输入输出线性化方法得到相对阶数为3的等价系统，该等价系统零动态渐近稳定。由于系统具有参数不确定性和未建模动态特性，采用了带积分的滑模变结构控制。实验结果表明，采用基于等效降阶模型的鲁棒控制，当模型存在误差时，能在关节的整个运动范围内实现较高精度的轨迹跟踪，且对气源压力和负载变化等外加干扰具有良好的鲁棒性。     

气动肌肉驱动关节的输入整形研究

为解决气动肌肉驱动关节在阶跃信号输入下的运动存在残余振荡的问题,提出了输入整形法。对关节的三种整形输入方式的特点进行了理论分析和试验研究。试验结果表明,选择适当的输入时滞时间和幅值可以有效地减小关节运动的残余振荡。提出的方法实现简单,效果好。