Alteration of mitochondrial bioenergetics due to intravenous injection of a perfluorocarbon emulsion

Wistar albino rats were intravenously injected with 1 ml of an oxyphoretic emulsion of perfluorobutylfurane and killed 3, 7 or 30 days later. Mitochondria isolated from the liver and kidneys of treated rats showed a small decrease in the transmembrane electrical potential and a substantial depression of the rates of both ATP synthesis and ADP-stimulated respiration. These alterations in mitochondrial oxidative phosphorylation appear to be induced by perfluorocarbon and/or tensioactive molecules interacting with hydrophobic cell structures.     

马齿苋多糖组分POP I对氧化损伤INS-1细胞的影响

目的：观察马齿苋多糖组分（POP I）对四氧嘧啶致大鼠胰岛素瘤细胞（INS-1 cell line）氧化损伤的影响.方法：不同浓度POP I （0.05,0.1,0.5,1.0,2.0,5.0和10.0 mg/mL）作用四氧嘧啶氧化损伤的INS-1细胞1d、3d和5d后,分别测定其细胞存活率、胰岛素分泌量、超氧化物歧化酶（SOD）活性、丙二醛（MDA）含量和谷胱甘肽（GSH）含量.结果：POP I可明显抑制由四氧嘧啶所致的INS-1细胞存活率降低、SOD活性下降、GSH浓度减少和.MDA含量增加,并存在时-效和量-效关系;在5.6 mmol/L或16.7 mmol/L葡萄糖刺激下,POP I浓度依赖性地促进了INS-1细胞分泌胰岛素.结论：一定浓度范围内,POPI对四氧嘧啶致胰岛β细胞损伤有明显的保护作用,其作用机理可能与POP I提高细胞抗氧化能力有关.     

黄精多糖对急性心肌梗死模型大鼠炎症及氧化应激反应的影响

摘要: 目的探讨黄精多糖( PSP) 对急性心肌梗死模型( AMI) 大鼠损伤的保护作用及可能机制。方法采用结扎冠状动脉左前降支的方法制备心肌梗死动物模型,假手术组只穿线不结扎,将造模成功的大鼠随机分为模型组、黄精多糖高、中、低剂量组( 900 mg /kg、450 mg /kg、225 mg /kg) 及阳性组( 麝香保心丸, 12. 2 mg /kg·d) ,每组10 只,每日灌胃1 次,连续4 周。分别记录造模前、造模即刻及给药1、3、7、10、14、21、28 d 心电图S-T 段变化,采用酶联免疫吸附法( ELISA) 测定各组大鼠血清中肿瘤坏死因子α( TNF-α) 、白介素6( IL-6) 、谷胱甘肽过氧化物酶( GSH-Px) 及丙二醛( MDA) 含量; 显微镜下观察受损心肌病理学的改变。结果与模型组相比,黄精多糖能明显抑制心肌梗死模型大鼠S-T 段的升高; 各给药组大鼠血清IL-6、TNF-α 水平均显著降低( P ＜ 0. 05 或0. 01) ,GSH-Px 活性升高( P ＜ 0. 05或0. 01) ,并降低MDA 含量( P ＜ 0. 05 或0. 01) ,心肌损伤程度明显改善。结论PSP 对急性心肌梗死模型大鼠心肌损伤有保护作用,其作用机制可能与减轻炎症反应,提高氧自由基清除能力,减少脂质过氧化损伤有关。     

折叠翼飞行器机翼折叠过程的颤振仿真分析

折叠翼是一种很有前景的变体飞行器设计方案.在折叠过程中,相当于飞机具有多个不同的机翼构型,所以其颤振特性将会发生剧烈的变化.为了提高求解效率,提出用准静态方法代替实时模拟方法来模拟折叠过程,并对折叠翼飞机进行了颤振特性的变参分析.得出了以下两个结论:1)当折叠角进入变体折叠的中间阶段时,机翼的颤振速压降低较大.2)折叠作动器的刚度会明显影响机翼的颤振速压.     

活性氧对生物大分子的氧化性损伤

活性氧在生物大分子如ＤＮＡ、蛋白质等氧化性损伤中起着非常重要的作用,本综述了活性氧的产生和氧化作用以及活性氧与一些病理过程的关系,对深入探讨生物大分子损伤的生物化及有关病理学机理具有一定的理论和应用意义。     

Respective roles of short-and long-range interactions in protein folding

A new method was presented to discuss the respective roles of short- and long-range interactions in protein folding. It‘s based on an off-lattice model, which is also being called as toy model. Simulated annealing algorithm was used to search its native conformation. When it is applied to analysis proteins lagt and laho, we find that helical segment catmot fold into native conformation without the influence of long-range interactions. That‘s to say that long-range interactions are the main determinants in protein folding.     

4-Hydroxynonenal-modified amyloid-beta peptide inhibits the proteasome: possible importance in Alzheimer's disease

The amyloid β-peptide (Aβ) is a 4-kDa species derived from the amyloid precursor protein, which accumulates in the brains of patients with Alzheimer’s disease. Although we lack full understanding of the etiology and pathogenesis of selective neuron death, considerable data do imply roles for both the toxic Aβ and increased oxidative stress. Another significant observation is the accumulation of abnormal, ubiquitin-conjugated proteins in affected neurons, suggesting dysfunction of the proteasome proteolytic system in these cells. Recent reports have indicated that Aβ can bind and inhibit the proteasome, the major cytoslic protease for degrading damaged and ubiquitin-conjugated proteins. Earlier results from our laboratory showed that moderately oxidized proteins are preferentially recognized and degraded by the proteasome; however, severely oxidized proteins cannot be easily degraded and, instead, inhibit the proteasome. We hypothesized that oxidatively modified Aβ might have a stronger (or weaker) inhibitory effect on the proteasome than does native Aβ. We therefore also investigated the proteasome inhibitory action of Aβ _1–40 (a peptide comprising the first 40 residues of Aβ) modified by the intracellular oxidant hydrogen peroxide, and by the lipid peroxidation product 4-hydroxynonenal (HNE). H₂O₂ modification of Aβ _1–40 generates a progressively poorer inhibitor of the purified human 20S proteasome. In contrast, HNE modification of Aβ _1–40 generates a progressively more selective and efficient inhibitor of the degradation of fluorogenic peptides and oxidized protein substrates by human 20S proteasome. This interaction may contribute to certain pathological manifestations of Alzheimer’s disease Received 26 September 2000; accepted 26 September 2000     

天津地区汉族7种不对称行为特征的研究

报道了天津市汉族956例(男462例,女494例)7项不对称行为特征(包括扣手、利手、叠臂、叠腿、利足、起步类型、优势眼),并与其他民族进行了比较.结果是:(1)天津地区汉族7项不对称行为特征中,有4项特征的R型出现率过半,其它3项R、L型分布相近;(2)7项不对称行为特征中,除利足、优势眼外其余5项出现率男女间差异不显著;(3)7项不对称行为特征中除叠臂外其余6项的出现率存在一定的民族差异;(4)不对称行为特征具有相关的数量较多,程度较高.     

Protein folding: concepts and perspectives

In this review, the main concepts of protein folding, as deduced from both theoretical and experimental in vitro studies, are presented. The thermodynamic aspects from Anfinsen's postulate, Levinthal's paradox to the concept of folding funnel as proposed by Wolynes and coworkers are described. Concerning the folding pathway(s), particular attention is brought to bear on the early steps that initiate the process in the light of the results of the fast and even ultrafast techniques presently being used. The role of structural domains as folding units is discussed. Last, from the recent studies, it can be concluded that the main rules deduced from the in vitro folding studies are valid for the folding of a nascent polypeptide chain in vivo.     

以硅藻土固载的过氧乙酸为氧化剂的吡唑啉脱氢芳构化反应研究

由吡唑啉脱氢芳构化去制备呲唑的氧化反应是被研究的.研究工作中用硅藻土固载的过氧乙酸作为氧化剂 ,对它在吡唑啉脱氢芳构化反应中的作用进行了探索,结果表明由过氧乙酸被硅藻土固载而构成的氧化剂组合,是一类有效而适用的脱氢芳构化试剂.