Phytanic acid impairs mitochondrial respiration through protonophoric action

Refsum disease is a rare, inherited neurodegenerative disorder characterized by accumulation of the dietary branched-chain fatty acid phytanic acid in plasma and tissues caused by a defect in the alphaoxidation pathway. The accumulation of phytanic acid is believed to be the main pathophysiological cause of the disease. However, the exact mechanism(s) by which phytanic acid exerts its toxicity have not been resolved. In this study, the effect of phytanic acid on mitochondrial respiration was investigated. The results show that in digitonin-permeabilized fibroblasts, phytanic acid decreases ATP synthesis, whereas substrate oxidation per se is not affected. Importantly, studies in intact fibroblasts revealed that phytanic acid decreases both the mitochondrial membrane potential and NAD(P)H autofluorescence. Taken together, the results described here show that unesterified phytanic acid exerts its toxic effect mainly through its protonophoric action, at least in human skin fibroblasts. Received 4 August 2007; received after revision 26 September 2007; accepted 10 October 2007 J. C. Komen, F. Distelmaier: These authors contributed equally to this work.     

Regulation of insulin receptor function

Resistance to the biological actions of insulin contributes to the development of type 2 diabetes and risk of cardiovascular disease. A reduced biological response to insulin by tissues results from an impairment in the cascade of phosphorylation events within cells that regulate the activity of enzymes comprising the insulin signaling pathway. In most models of insulin resistance, there is evidence that this decrement in insulin signaling begins with either the activation or substrate kinase activity of the insulin receptor (IR), which is the only component of the pathway that is unique to insulin action. Activation of the IR can be impaired by post-translational modifications of the protein involving serine phosphorylation, or by binding to inhibiting proteins such as PC-1 or members of the SOCS or Grb protein families. The impact of these processes on the conformational changes and phosphorylation events required for full signaling activity, as well as the role of these mechanisms in human disease, is reviewed in this article. Received 3 August 2006; received after revision 1 December 2006; accepted 8 January 2007     

预应力水冲桩抗裂性能研究分析

某码头工程下部结构采用预应力水冲锤击桩,试桩过程中发现,在贯入度较大的情况下桩身多处产生横向裂缝,使桩尖无法达到设计标高。为分析产生裂缝原因,通过静荷载试验的方法检验桩身的抗裂性能;结果表明张拉控制应力未达到设计值,是导致桩身产生环向裂缝的主要原因;提出适当调整预应力,能够有效地解决预应力水冲桩桩身裂缝的问题。     

膜法分离纯化葛根素的实验研究

采用陶瓷膜技术过滤粗葛根素溶液,渗透通量为200~350 L.h-1.m-2。采用GH4040型超滤膜处理微滤渗透液,在37℃和1.50 MPa下超滤渗透通量可以达到13.02 L.h-1.m-2,葛根素的截留率约为87%。采用膜技术分离纯化葛根素具有良好的发展前景。     

铁磁/半导体/铁磁隧道结中的隧穿磁电阻

采用相干量子输运理论和传递矩阵方法研究了具有不同自旋指向的极化电子渡越铁磁/半导体/铁磁隧道结的隧穿几率和隧穿磁电阻。研究表明隧穿几率和隧穿磁电阻随半导体长度的改变发生周期性变化、随Rashba自旋轨道耦合强度的改变发生准周期变化,并且在两铁磁电极中磁矩取向平行时,选择适当的半导体的长度和Rashba自旋轨道耦合强度可以得到较大的隧穿磁电阻。     

用于盐酸阿霉素增敏的双给药水凝胶体系制备

多药耐药型乳腺癌细胞对抗癌药物盐酸阿霉素(DOX·HCl)敏感性下降,需要设计和制备一种实现抗癌药物增敏的给药体系.提出一种同时负载DOX·HCl和齐墩果酸(OA)的双给药聚乙二醇水凝胶体系.该体系基于具有亲水和疏水性的聚乙二醇水凝胶,实现DOX·HCl和OA的共包封和共释放.两种药物的释放通过氧-迈克尔加成反应和醇修...     

闽南地区农村住宅安全性现状及防灾建议

在对厦门市海沧区近9 000栋农村住宅的安全性和耐久性现状普查基础上,分析该地区农村住宅的结构类型分布特点和不同类型房屋的安全性等级分布.针对该地区农村住宅存在的安全性和耐久性问题,提出该地区农村住宅防御自然灾害,特别是防御地震灾害的相关建议.     

不同pH值对Au/CaM膜结合Ca2+的电化学行为研究

采用交流阻抗的方法,在包含1 mmol/L Fe(CN)63-/4-的0.15 mol/L的NaCl溶液中,研究了Au/CaM膜在不同的酸碱环境下结合Ca2 的电化学行为.结果表明:在pH为6.5的环境下Au/CaM膜结合Ca2 的能力要比在pH为4.5环境下的强.     

被动伸展与抗阻功能相结合的训练方法研究

被动伸展与抗阻功能相结合的运动,是一种综合了医疗体育的3种康复运动(被动运动、伸展运动、抗阻运动)特点的运动,不仅对运动创伤有康复作用,而且还可以起到预防运动创伤、提高运动能力的作用.由于其适用范围广,可操作性强,能对人体许多部位进行专项功能训练,具有推广价值.     

Ni-P化学镀层镀后封闭工艺的研究

对化学镀Ni-P合金镀层进行了镀后封闭处理的工艺研究,包括封闭剂的选择、封闭时间、温度、pH值等的确定.通过孔隙率的测定和中性盐雾实验,结果表明含5%K2Cr2O7的复合封闭剂在pH=5、温度50℃条件下具有较好的封闭作用,可显著提高化学镀Ni-P镀层的耐蚀性能.