番茄红素对镉诱导睾丸损伤大鼠抗氧化酶活性及生殖激素水平的影响

目的观察番茄红素对镉诱导睾丸损伤大鼠抗氧化酶活性及生殖激素水平的影响。方法将28只雄性SD大鼠随机分为4组,每组7只,分别为空白对照组、5 mg/L镉组、5 mg/L镉+10 mg/kg番茄红素组、5 mg/L镉+20 mg/kg番茄红素组,给药1周后处死,测定睾丸组织超氧化物歧化酶(SOD)、丙二醛(MDA)、谷胱甘肽过氧化物酶(GSH-Px)活性及血清促黄体生成素(LH)、睾酮(T)水平。结果镉组大鼠体质量、睾丸质量、睾丸组织SOD、GSH-Px活性及血清T水平均显著低于NC组(P0.01),睾丸组织MDA含量和血清LH水平则显著高于后者(P0.01);番茄红素可缓解染镉大鼠体质量和睾丸质量的减轻,并回调抗氧化酶活性和生殖激素水平,且高剂量组效果更为显著。结论番茄红素对染镉大鼠的睾丸损伤具有剂量依赖性的改善作用,可能与清除氧自由基和抗脂质过氧化有关。     

泽泻三萜类成分的提取工艺优化及活性评价

建立泽泻中三萜类成分的最佳提取工艺,并考察其对老年性耳聋小鼠血清生理学指标的影响。通过正交试验优化泽泻三萜类成分的提取工艺,并用紫外分光光度法(UV)测定含量。采用D-半乳糖建立小鼠老年性耳聋模型,灌胃给予泽泻三萜类成分提取物后,测定小鼠血清丙二醛(MDA)含量和超氧化物歧化酶(SOD)活力。结果表明:泽泻三萜类成分的最佳提取工艺为:料液比1∶8,85%乙醇超声提取60 min,重复提取2次。通过D101大孔吸附树脂纯化后,泽泻三萜类成分的平均含量为4.55%。给药后,样品组小鼠血清SOD值较模型组明显升高,但MDA值变化不明显。所建立的最佳提取工艺具有较好的收率、稳定性以及可行性。     

调节肽在休克发病中的作用

本文探讨了三种调节肽在休克发病中的作用。结果表明:(1)败血症休克大鼠血浆内皮素(ET)成倍增加,给健康大鼠持续滴注低剂量ET可致明显的休克表现,而给轻度失血休克大鼠静滴ET,则致休克不可逆,用特异的ET-抗血清治疗休克,具有明显疗效;(2)败血症休克大鼠血浆降钙素基因相关肽(CGRP)增加2.6倍,休克早期或晚期运用低剂量CGRP治疗都具有显著疗效;(3)休克大鼠心肌、主动脉组织血管紧张素Ⅱ明显增加,休克早期抑制其增加可加剧休克,晚期抑制其升高则具有显著疗效.结论认为,ET是参与休克发病的重要体液因素,CGRP参与休克时机体的代偿调节,组织血管紧张素Ⅱ在休克不同时期作用不同。     

微量元素、抗氧化剂与湿热证的相关性的研究

建立了温病湿热证动物模型，研究了清香散对大鼠微旦元素锌（Zn）、硒（Se)、铜（Cu)和维生素E代谢水平，一氧化氮（NO）含量以及谷胱甘肽过氧化物酶（GSH－Px)活力变化的影响，并将正常对照组、湿热模型组、清香散治疗组进行两两比较。结果表明，湿热证模型大鼠血清Zn、Se、维生素E、NO含量显著下降，Cu含量显著升高，GSH－Px活力明显降低，经清热祛湿的经验方清香散治疗后，大鼠血清Zn、Se、维生素E、NO含量及GSH－Px活力明显升高，Cu含量明显下降。抗氧化能力下降是湿热证的本质之一，微量元素锌（Zn)、硒（Se)、铜（Cu)在机体内的含量反映了抗氧化酶活性的高低，清香散能显著提高大鼠血液Zn、Ee、维生素E、NO含量及GSH－Px活力，降低Cu含量，恢复其抗氧化能力。     

番茄红素改善移植血管内皮功能

目的探讨番茄红素对大鼠移植血管内皮功能的改善作用。方法实验分为两组:实验组,Lewis大鼠接受Brown-Norway(BN)大鼠腹主动脉移植;番茄红素干预组(30 mg·kg-1·d-1),Lewis大鼠接受BN大鼠腹主动脉移植。于移植后28 d取移植动脉,进行组织形态学观察、测量内膜厚度,免疫组化检测血管内i NOS和ICAM-1表达。收集各组血浆,ELISA检测c GMP浓度。结果各组血管内膜均出现增厚;番茄红素干预组血管内膜增厚与实验组相比显著降低,差异有统计学意义(P0.05)。免疫组化检测结果显示,与实验组相比,番茄红素干预组移植动脉i NOS表达增高(P0.05)。结论番茄红素通过调控NOS通路,改善内皮功能,缓解移植动脉的纤维化进程以及内膜的增生。     

冷应激对铜预投大鼠血清铜锌代谢、SOD活性及GSH含量的影响

为揭示应激对体内微量元素代谢的影响和机制，预先给予大鼠不同水平的铜3周后，采用冷束缚法使大鼠产生应激，测定了血清铜、锌水平及超氧化物歧化酶(SOD)活性、还原型谷胱甘肽(GSH)和丙二醛(MDA)含量。结果表明，高铜给予没有对清洁级大鼠生长产生明显的影响．血清铜、锌及铜锌比值变化不明显，但适量的铜给予能显著提高血清中SOD活性和GSH含量；冷应激处理后大鼠血清中Cu水平下降，Zn水平升高，同时SOD消耗降低，而GSH含量显著升高。表明冷应激可使大鼠体内铜锌代谢及SOD活性和GSH含量发生变化，适量的铜给予在应激状况下才发挥出积极的生理作用。     

血管内皮舒张因子激活阻力血管平滑肌细胞钙激活钾通道

本实验直接观察了由10~(-6)mol/L Ach激发大鼠主动脉内皮细胞产生的血管内皮舒张因子(Endothelium-derived relaxing factor,简称EDRF)对大鼠肠系膜动脉阻力血管平滑肌细胞钙激活钾通道的作用,首次发现EDRF可激活阻力血管平滑肌上160.3pS,76.4pS两种不同电导的钙激活钾通道。将目前有人认为是EDRF主要活性成分的NO(通过10~(-8)mol/L硝普钠释放)作用于相同标本上可激活100.5pS的钙激活钾通道。动力学分析表明EDRF与NO作用性质有差异。特别是通道开放概率,EDRF激活者远较NO激活者大。     

基于同源建模和定点突变技术研究嗜热型L-阿拉伯糖异构酶与D-半乳糖的亲和作用

通过同源建模分析选取对Lactobacillus fermentum CGMCC2921来源的L-阿拉伯糖异构酶(简称L-AI酶)催化D-半乳糖生产D-塔格糖起重要作用的氨基酸位点进行突变,发现当Q16,M311,K423和Q438位点的氨基酸突变为丙氨酸时,突变酶Km值降低,其中突变酶M311A降至本体的51.6%,对D-半乳糖的转化率提高了18.7%.当K423位点的氨基酸残基分别突变为丙氨酸、天冬酰胺或精氨酸时,突变酶与底物的亲和力以及D-半乳糖的转化率随着423位点突变氨基酸侧链长度的增加而降低.运用计算机分子模拟技术分析表明,当M311位点氨基酸突变为丙氨酸以后,催化位点氨基酸残基与底物D-半乳糖之间的氢键作用增强,导致与底物亲和力增大,从而提高了酶活力.     

亚慢性Sm(NO_3)_3暴露对小鼠肝脏的影响

探讨Sm(NO_3)_3亚慢性暴露对小鼠肝功能、肝脏组织结构、酶活的影响。ICR小鼠80只,雌雄各半,随机分成5组,分别自由饮用0,5,50,500,2000 mg·L~(-1)的Sm(NO_3)_3溶液90 d,测定小鼠肝功能指标及肝脏组织SOD,GSH-Px,CAT活力及MDA含量,肝脏光镜切片观察肝组织形态学的变化。结果显示60,90 d 2000 mg·L~(-1)雌性组体重、雄性组肝脏脏器系数与对照组相比具有显著下降(P0.05);2000 mg·L~(-1)AST雌雄性组、ALT雄性组、Urea雌性组与对照相比具有显著升高(P0.05),ALB雄性组与对照相比显著降低(P0.05);GSH-PX活力5,50 mg·L~(-1)雄性组与对照组相比有极显著升高(P0.01),而500,2000 mg·L~(-1)组雄性鼠有极显著和显著下降(P0.01,P0.05),SOD活力在500,2000 mg·L~(-1)雌雄组与对照组相比有显著和极显著降低(P0.05,P0.01),MDA在50,500,2000 mg·L~(-1)雌性组与对照相比有显著与极显著升高(P0.05,P0.01),CAT 500,2000 mg·L~(-1)雄性组与对照组相比有显著降低(P0.05);500 mg·L~(-1)组肝细胞肿大,胞质疏松,肝窦、中央静脉有狭窄,2000 mg·L~(-1)细胞排列紊乱,细胞界限不清,部分肝窦狭小甚至完全闭塞,少数肝细胞有破裂现象。以上结果表明亚慢性Sm(NO_3)_3暴露可导致小鼠肝功能异常、肝组织结构损伤,并与暴露浓度、时间及性别相关;提示氧化损伤可能是亚慢性Sm(NO_3)_3暴露致小鼠肝脏毒性损伤的作用机制之一。     

铜中毒对SD大鼠肝的影响研究

将36只雄性大鼠80~100 g随机分为3组,分别喂以对照日粮(Cu质量分数13.15mg/kg)和高铜日粮(Cu质量分数650、850 mg/kg),实验期为9周,进行了铜中毒对大鼠肝脏影响的病理学研究。结果表明,与对照组比较,高铜Ⅰ、Ⅱ组大鼠肝脏出现不同程度的病理损害;大鼠肝脏脏器系数有增高趋势,但差异无显著(P0.05)。同时,乳酸脱氢酶、谷草转氨酶活性显著升高(P0.01),血清铜含量上升,SOD含量下降。提示日粮铜质量分数650~850 mg/kg即可引起大鼠肝脏的病理损伤,功能降低。     

无规聚苯乙烯物理老化的研究历史和进展

系统地总结了有关无规聚苯乙烯的物理老化的工作，分析了几种物理老化动力学理论模型的特点和不足；展望了物理老化研究的未来。     

紫外光固化材料热老化黄变的研究

本文通过监测添加不同类型和不同比例的抗氧剂的紫外光固化材料在热老化过程中黄变因数的变化,来考察抗氧剂对紫外光固化材料热老化黄变的影响和不同的抗黄变能力.利用紫外-可见光谱仪表征老化过程试样的透光率,结果表明,抗氧剂能很好地减小紫外光固化材料的热老化黄变,抗氧剂中的羟基的抗黄变能力存在差异,决定了抗氧剂的抗黄变能力.Irgafos-168分别与Ir-ganox-1010和Irganox-1076复配时,表现出较好的协同效应,从而使复配抗氧剂的抗黄变能力比单组分抗氧剂的抗黄变能力强.     

Y-TZP材料低温老化研究进展

对Y-TZP材料低温老化现象、影响因素及其抑制方法作了综合评述.     

The Effects of Physical Aging on Tensile Behavior of Polyphenylquinoxaline Films

Themechanicalpropertiesareaffectedbyphysicalaging'.P0lyphenylquin0xaline(PPQ-E)-anar0maticheter0cyclicpolymer-hasmanyusesduetoitshighperformance2'.Theaimofthepaperistostudytheeffects0fphysicalagingontensilepr0pertyf0rPPQ-Efilms.T0avoidnewphysicalagingeffectduringstretchingl4.tensiletestmeth0df0rnotchedspecimensandDSCmeasurementareusedintheexperiments.ExperimentaIThePPQ-Esynthesizedinthelab0ratorywascastintoafilmO.O5mminthickness,whichwasthencutintorectangularspecimenDf35rnmlongandl.7mm…     

The Nonlinear Viscoelastic Response of Glassy Polymers Subjected to Physical Aging

Constitutive equations are developed for the nonlinear viscoelastic behavior of amorphous glassy polymers in the sub‐yield region. A polymeric glass is treated as an ensemble of cooperatively rearranging regions bridged by links. Stress‐strain relations are derived and verified by comparison with experimental data in static mechanical tests on polycarbonate and poly(methyl methacrylate). We analyze the effects of the straining state (tension, compression and torsion), strain intensity, temperature and time of annealing on stress relaxation. Fair agreement is demonstrated between observations and results of numerical simulation.     

Aging of quenched polypropylene

Structural changes occurring during the aging of polypropylene quenched from the melt have been investigated by measurements of gas transport parameters and mechanical properties. Major changes in diffusion and sorption behavior during the first 30 hr of aging at room temperature were found to be strongly dependent on the atomic size of the inert gas penetrants. Tensile mechanical properties increased with aging time, while resilience and mechanical damping showed more complex behavior. The interpretation of the combined results suggests that the aging process may involve molecular rearrangements generally comparable to those for secondary crystallization processes, but within domains comparable in size to that of the smaller penetrant species. The relaxation of a residual stress distribution related to nonuniform plastic flow during quenching may be superimposed on the rearrangement phenomena.     

Al-Zn-Mg-Cu合金双级时效析出行为的TEM研究

Al-Zn-Mg-Cu合金是一种时效强化高强变形铝合金,长期以来广泛应用于航空航天等工业领域[1,2].其性能主要由时效过程中的时效析出相决定.研究不同时效状态下合金时效析出相的显微组织结构,对明确组织与性能的关系、确定合理的热处理工艺、改善合金的综合性能具有重要的理论意义和工程实用价值.     

Aging of Transformer Insulation Paper

Abstract

As a transformer ages, the chemical and physical properties of the cellulose insulation materials in the transformer change, and the paper loses its strength and becomes brittle. The average molecular weight of the cellulose chains decrease with age, and degradation products are formed, including water, carbon monoxide, carbon dioxide, and furans. The molecular weight changes in the cellulose have been studied by several methods, but the GPC method for determination of the molecular weight has been shown to offer advantages over other methods because it yields the total molecular weight distribution. The tensile strength of the cellulose insulation in transformers also changes with age as a result of the changing molecular weight of the cellulose. Work carried out in our laboratory on the aging of cellulose insulation is reviewed in this paper. Our studies have included investigations of insulation materials from retired transformers as well as accelerated aging of insulation paper in transformer oil in the temperature range of 129–166°C under vacuum. In the study the relationships between the molecular weight of the cellulose and the furan degradation products and tensile strength have been delineated, and they have been correlated with information on the kinetics of degradation of the insulation paper.     

Lipid Biomarkers of Lens Aging

Lipids are important structural components of cell membranes and have profound effect on membrane fluidity. Lipid profiling and lipidomics have captured increased attention due to the well-recognized roles of lipids in numerous human diseases. Investigating lipid profiles not only provides insights into the specific roles of lipid molecular species in health and diseases, but can also help in identifying potential preventive or therapeutic biomarkers. Cataract, the loss of transparency of eye lens, is a disease of protein aggregation. There are several factors contributing to the stability in protein conformation. Age-related changes in lipid composition could be a contributing factor for altered protein–lipid interaction leading to protein aggregation and cataract. Keeping this in view, in the present study, fatty acid profiling from different age groups of lenses was carried out, using a freshwater catfish as the model. Total lipids were extracted from lenses of three different age groups of fishes (young, adult, and aged) and fatty acid methyl esters (FAME) were prepared and FAME analysis was carried out using gas chromatography–mass spectrometry. The results showed that three fatty acids viz. heneicosylic acid (C21), docosahexaenoic acid (C22:6), nervonic acid (C24:1) which were not present in the adult lens, appeared in the aged lens. On the other hand, eicosenoic acid (C20:1) present in the adult lens was found to be absent in the aged lens. The appearance or disappearance of these fatty acids can possibly serve as biomarkers of aging lens which is the most vulnerable stage for cataract development.     

Green Tea Suppresses Brain Aging

Epidemiological studies have demonstrated that the intake of green tea is effective in reducing the risk of dementia. The most important component of green tea is epigallocatechin gallate (EGCG). Both EGCG and epigallocatechin (EGC) have been suggested to cross the blood–brain barrier to reach the brain parenchyma, but EGCG has been found to be more effective than EGC in promoting neuronal differentiation. It has also been suggested that the products of EGCG decomposition by the intestinal microbiota promote the differentiation of nerve cells and that both EGCG and its degradation products act on nerve cells with a time lag. On the other hand, the free amino acids theanine and arginine contained in green tea have stress-reducing effects. While long-term stress accelerates the aging of the brain, theanine and arginine suppress the aging of the brain due to their anti-stress effect. Since this effect is counteracted by EGCG and caffeine, the ratios between these green tea components are important for the anti-stress action. In this review, we describe how green tea suppresses brain aging, through the activation of nerve cells by both EGCG and its degradation products, and the reductions in stress achieved by theanine and arginine.