l‐Citrulline Supplementation‐Increased Skeletal Muscle PGC‐1α Expression Is Associated with Exercise Performance and Increased Skeletal Muscle Weight

Scope

l ‐citrulline has recently been reported as a more effective supplement for promoting intracellular nitric oxide (NO) production compared to l ‐arginine. Here, the effect of l ‐citrulline on skeletal muscle and its influence on exercise performance were investigated. The underlying mechanism of its effect, specifically on the expression of skeletal muscle peroxisome proliferator‐activated receptor‐gamma coactivator‐1α (PGC‐1α), was also elucidated.

Methods and results

Six‐week‐old ICR mice were orally supplemented with l ‐citrulline (250 mg kg^?1) daily, and their performance in weight‐loaded swimming exercise every other day for 15 days, was evaluated. In addition, mice muscles were weighed and evaluated for the expression of PGC‐1α and PGC‐1α‐regulated genes. Mice orally supplemented with l ‐citrulline had significantly higher gastrocnemius and biceps femoris muscle mass. Although not statistically significant, l ‐citrulline prolonged the swimming time to exhaustion. PGC‐1α upregulation was associated with vascular endothelial growth factor α (VEGFα) and insulin‐like growth factor 1 (IGF‐1) upregulation. VEGFα and IGF‐1 are important for angiogenesis and muscle growth, respectively, and are regulated by PGC‐1α. Treatment with NG‐nitro‐l ‐arginine methyl ester hydrochloride (l ‐NAME), a nitric oxide synthesis inhibitor, suppressed the l ‐citrulline‐induced PGC‐1α upregulation in vitro.

Conclusion

Supplementation with l ‐citrulline upregulates skeletal muscle PGC‐1α levels resulting in higher skeletal muscle weight that improves time to exhaustion during exercise.

     

Discovery and Evaluation of a Functional Ternary Polymer Blend for Bone Repair: Translation from a Microarray to a Clinical Model

Skeletal tissue regeneration is often required following trauma, where substantial bone or cartilage loss may be encountered and is a significant driver for the development of biomaterials with a defined 3D structural network. Solvent blending is a process that avoids complications associated with conventional thermal or mechanical polymer blending or synthesis, opening up large areas of chemical and physical space, while potentially simplifying regulatory pathways towards in vivo application. Here ternary mixtures of natural and synthetic polymers were solvent blended and evaluated as potential bone tissue engineering matrices for osteoregeneration by the assessment of growth and differentiation of STRO‐1+ skeletal stem cells. Several of the blend materials were found to be excellent supports for human bone marrow‐derived STRO‐1+ skeletal cells and fetal skeletal cells, with the optimized blend exhibiting in vivo osteogenic potential, suggesting that these polymer blends could act as suitable matrices for bioengineering of hard tissues.     

基于衰老视角评析肌少症实验药理模型的研究进展

肌少症主要表现为骨骼肌质量、力量和功能的进行性下降,已经成为老年肌肉骨骼系统的主要慢性疾病之一。在基础研究中,可靠的实验模型对于深入理解肌少症的病理生理机制以及新药研发具有重要意义。本文初步总结了衰老诱导肌少症的潜在机制,并重点从体外细胞模型、体内动物模型,讨论基于衰老分子机制的肌少症药理模型的研究进展。     

高浓度CaCl2溶液对某些肌原纤维蛋白的作用研究

用0、100、200、300mmol/LCaCl2溶液处理肌球蛋白、肌动蛋白和肌原纤维,通过SDS-PAGE和免疫印迹电泳研究100、200、300mmol/L高浓度CaCl2溶液处理下肌球蛋白、肌动蛋白、α-肌动素和肌钙蛋白-T的蛋白降解情况。SDS-PAGE结果显示,肌球蛋白、肌动蛋白在100、200、300mmol/LCaCl2溶液处理下1、7d时的电泳结果与对照组相比没有显著差异。免疫电泳结果显示,100、200、300mmol/L高浓度CaCl2溶液处理后,α-肌动素和肌钙蛋白-T与对照组相比发生显著降解,随着浓度升高,降解程度加大,在300mmol/L浓度时,α-肌动素条带密度显著降低,肌钙蛋白-T也裂解为30kD以下的更小片段。     

正向近冰点温度下肉牛骨骼肌主要生化指标变化特性的研究

本文对30头肉牛宰后经电刺激的胴体从背最长肌肉处取样在近冰点温度(1～-1℃)下贮存10d过程中游离Ca2+、ATP、总游离氨基酸、糖原、失水率的变化进行了研究。结果表明,10d中糖原、总游离氨基酸、ATP、失水率的变化几乎是同步的,均在刚宰后的0～1d(24h)中变化明显,第2d(48h)是转折点,而游离Ca2+第3d(72h)是转折点。作出了相应的变化曲线图,对指标间作Pearson相关性分析表明:游离钙与可溶性磷、游离钙与失水率、可溶性磷与失水率、糖原与总游离氨基酸、糖原与可溶性磷之间相关系数均极显著(p<0.01);游离钙与糖原之间相关系数显著(p<0.05);并且得出了相应的相关方程。对牛肉样的五项指标进行综合分析可知:所测定的牛肉样品在宰后约13.5h就进入了僵直起始阶段,而到宰后接近48h僵直达到了最大化。     

Interaction of hydrogen and n‐pentane with sulfated zirconia

Interaction of hydrogen with sulfated zirconia catalysts was studied in situ at 473 K. Interaction of hydrogen with the sample evacuated at 673 K leads to the formation of new hydroxyl groups (wide bands near 3330 cm⁻¹) and water (1620 cm⁻¹). In the case of the sample evacuated at 873 K, SOH groups (3660 cm⁻¹) and zirconium hydrides (1555 cm⁻¹) form. Adsorption of n‐pentane on sulfated zirconia catalysts in the range of 253–383 K was studied. It was shown that hydrides and protonated cyclopentadienes form at low temperatures. At higher temperatures, aromatic compounds are formed mainly. The reaction mechanism is discussed. This revised version was published online in August 2006 with corrections to the Cover Date.     

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。     

多轴应力状态下P91钢蠕变寿命损耗的研究

根据单轴及多轴实验数据,运用ANSYS有限元方法,对高温P91钢蠕变进行研究。基于用户可编程特性,将含有损伤-硬化蠕变模型的程序写入ANSYS,该模型对含有第三区蠕变的模拟取得较好的效果。研究了在高温下金属材料多轴蠕变的骨点应力(Skeletal Point Stress)以及断裂时间与单轴蠕变的关系。对高温高压状态下弯头发生蠕变效应进行分析,指出蠕变效应对弯头部位应力变化的影响,通过对骨点应力的分析,得出弯头部件蠕变损耗的变化情况。研究结果为正确预测高温高压弯头部件的剩余寿命提供了理论依据。     

基于Kinect骨骼跟踪技术的人机交互

基于Kinect提供的深度信息和骨骼跟踪技术进行手势识别,利用手势代替鼠标实现人机交互.首先,引入以人体为参考系的人体坐标系统,将手势位置通过坐标系变换映射到计算机屏幕,实现计算机屏幕上光标的位置显示和跟踪.其次,研究计算机操作系统响应鼠标事件的工作模式,设计固定的手势静态及动态工作模式,通过一定的映射关系将特定的一组手势与计算机系统基本操作指令进行对应.并定义状态机,根据手势状态触发系统操作事件,从而达到对计算机系统的体感控制.实验表明,该人机交互系统自然、合理、有效.     

Effect of Long-Term Supplementation with Acetic Acid on the Skeletal Muscle of Aging Sprague Dawley Rats

Mitochondrial function in skeletal muscle, which plays an essential role in oxidative capacity and physical activity, declines with aging. Acetic acid activates AMP-activated protein kinase (AMPK), which plays a key role in the regulation of whole-body energy by phosphorylating key metabolic enzymes in both biosynthetic and oxidative pathways and stimulates gene expression associated with slow-twitch fibers and mitochondria in skeletal muscle cells. In this study, we investigate whether long-term supplementation with acetic acid improves age-related changes in the skeletal muscle of aging rats in association with the activation of AMPK. Male Sprague Dawley (SD) rats were administered acetic acid orally from 37 to 56 weeks of age. Long-term supplementation with acetic acid decreased the expression of atrophy-related genes, such as atrogin-1, muscle RING-finger protein-1 (MuRF1), and transforming growth factor beta (TGF-β), activated AMPK, and affected the proliferation of mitochondria and type I fiber-related molecules in muscles. The findings suggest that acetic acid exhibits an anti-aging function in the skeletal muscles of aging rats.