Lipid Peroxidation. Definition of Experimental Conditions for Selective Study of the Propagation and Termination Phases

To find experimental conditions to selectively study the propagation phase of lipoperoxidation we studied the lipoperoxidation, catalyzed by FeCl₂, of liposomes in a buffering condition where Fe²⁺ autoxidation and oxygen active species generation does not occur. Liposomes from egg yolk phosphatidylcholine. prepared by vortex mixing, do not oxidize Fe²⁺: on the contrary they oxidize Fe²⁺ when prepared by ultrasonic irradiation. Dimyristoyl phosphatidylcholine liposomes prepared by ultrasonic irradiation do not oxidize Fe²⁺. During sonication polyunsaturated fatty acid residues autoxidize and lipid hydroperoxides (LOOH) are generated. Only when LOOH are present in the liposimes Fe²⁺ oxidizes and its rate of oxidation depends on the amount of LOOH in the assay. The reaction results in the generation of both LOOH and thiobarbituric acid reactive material (TBAR): it is inhibited by butylated hydroxytoluene and has a acidic pH optimum; it is not inhibited by catalase and OH' scavengers. The reaction studied. thus, appears to be the chain branching and propagation phase of lipoperoxidation. When we studied the dependence of Fe²⁺ oxidation, LOOH and TBAR generation on FeCl₂ concentration, we observed that at high FeCl₂ concentrations the termination phase of lipoperoxidation was prevalent. Thus. by selecting the appropriate FeCl₂ concentration the proposed experimental system allows study of either the propagation or the termination phase of lipoperoxidation.     

莲心碱对实验性高脂血症大鼠血脂及脂质过氧化的影响

本文研究莲心碱对实验性高脂血症大鼠血脂和抗氧化能力的影响.将32只大鼠随机分为4组,对照组饲喂基础饲料;诱导组饲喂高脂饲料;试验组给予高脂饲料+莲心碱灌胃2.5和5.0 mg·kg-1.测血清中血脂和丙二醛(MDA)水平,以及谷胱甘肽过氧化物酶(GSH-Px)、超氧化物歧化酶(SOD)活性;取肝脏测绝对和相对肝重及MDA含量.结果表明莲心碱可显著降低实验性高脂血症大鼠血清中总胆固醇、甘油三酯、低密度脂蛋白胆固醇水平和动脉粥样硬化指数;显著升高血清高密度脂蛋白胆固醇、GSH-Px和SOD水平;同时还可显著降低血清和肝脏中MDA的含量;其绝对和相对肝重均低于诱导组.     

苦参组培快繁技术体系的初步研究

采用正交实验设计(L934)用MS、White和改良MS培养基,分别加入不同质量浓度的玉米素(ZT)、6-苄基氨基腺嘌呤(6-BA)、异戊烯基腺嘌呤(2-ip)进行苦参组培快繁技术体系研究。结果表明,以苦参种子萌发的幼苗为外植体效果较好。3种基本培养基对诱导芽增殖效果差异不显著;在基本培养基中分别加入6-BA、2-ip和ZT诱导芽增殖,但3种细胞分裂素之间差异不显著。培养基中含2 mg/L 6-BA(或ZT或2ip)增殖效果最好,其次是3mg/L的细胞分裂素;以改良MS 2 mg/L 6-BA是苦参较好的增殖培养基;组培苗在1/2 MS 1.5 mg/L IBA培养基上根诱导效果最好(98%),移栽到珍珠岩 蛭石基质(1∶1)中成活率最高(96%)。     

Melanins in Physiological Conditions Protect Against Lipoperoxidation. A Study on Albino and Pigmented Xenopus

The susceptibility to lipoperoxidation in liver of albino and pigmented Xenopus laevis Daudin, has been studied. Albino Xenopus liver was richer in polyunsaturated fatty acids (PUFAs) than the pigmented one; moreover, it was also richer in mitochondrial superoxide dismutase (MnSOD) and in reduced glutathione (GSH). The thiobarbituric acid-reactive substances (TBARS) values were more abundant in the albino tissue compared to the pigmented tissue both during spontaneous and Fe⁺⁺ induced lipoperoxidation. Therefore, when isolated and purified melanin, in physiological quantities, was added to albino tissue, the TBARS values drastically decreased. Thus, melanin, in our experimental conditions, protects the albino tissue even more than SOD and GSH do. Melanin, in our opinion, acts as an antioxidant, because it is able to scavenge O₂^?.     

两种观赏蕨类植物的繁殖技术研究

探讨了江南星蕨和庐山石韦两种观赏蕨类的繁殖技术。分株繁殖主要在春季进行,并注意日常管理。两种蕨类的孢子繁殖采用5种基质对照,经试验,江南星蕨孢子繁殖的基质以泥炭土：蛭石：珍珠岩：2：1：1为最佳,而庐山石韦则以基质泥炭土：蛭石=2：1为最好。     

Possible Regulatory Effect of Lipid Peroxidation on the H+-ATPase Activity of the Plasmalemma under Stress Conditions

We studied the effects of high temperature and paraquat on the rate of lipid peroxidation and activity of the H⁺-ATPase in the plasmalemma fraction isolated from pea leaves. We demonstrated a heat-induced increase in both indices. When lipid-peroxidation was inhibited by pretreatment with butylated hydroxytoluene, a synthetic antioxidant, the H⁺-ATPase activity increased to a lesser extent than after heat shock without pretreatment. Treatment of plants with paraquat, a prooxidant causing an oxidative stress, resulted in a dramatic increase in lipid peroxidation and H⁺-ATPase activity. We suggested that the enhanced lipid peroxidation could be one of the causes for the H⁺-ATPase activation in the plasmalemma under stress conditions.     

白及种子萌发与快速繁殖技术的研究

将不同胚龄的白及种子接种到不同培养基中进行培养,对白及种子萌发率、萌发时间、丛生芽增殖、生根等方面进行了研究。结果表明:白及种子萌发率与其胚龄及有胚率成正相关,萌发时间则与胚龄及有胚率成负相关;胚龄16周的种子在1 g/L花宝1号 2 g/L花宝2号的培养基上萌发率可达84%;胚龄等于或大于20周的种子萌发率不受培养基成分的影响,均可达100%,萌发时间只需7 d;丛生芽增殖的最佳培养基为1/2 MS 4.0 mg/L6-BA 0.2 mg/L NAA 100 g/L CM,其增殖倍数达4.41倍;诱导生根较好的培养基为1/2 MS 0.2 mg/L NAA,生根率达90%。     

Lipid Peroxidation in Hyperlipidaemic Patients. A Study of Plasma using an HPLC-Based Thiobarbituric Acid Test

The question of “increased lipid peroxidation” in plasma from hyperlipidaemic patients was investigated using an improved HPLC-based assay for thiobarbituric acid-reactive material. Levels of TBARS in healthy human controls were at or close to zero, provided that butylated hydroxytoluene was added to the sample with the TBA reagents. Levels of plasma TBARS in hyperlipidaemic patients were elevated, although the absolute levels were much lower than those reported previously in the literature.     

荷兰菊组织培养快繁技术研究

本文利用组织培养技术研究荷兰菊的快速繁殖,为大量培育荷兰菊种苗提供可靠方法。通过多种培养基的试验筛选,找出较满意的培养方法、三种培养基依次使用,可以达到快速繁殖目的。三种培养基分别是：ＭＳ＋ＫＴＯ·ｌｍｇ／ｌ＋糖２０９／１＋琼脂７ｇ／ｌ、ＭＳ＋６—ＢＡ５ｍｇ／ｌ＋ＮＡＡＯ．０１ｍｇ／ｌ＋糖２０９／ｌ＋琼脂７ｇ／ｌ、１／ＺＭＳ＋ＮＡＡＯ．ｌｍｇ／ｌ＋糖２０ｇ／ｌ＋琼脂７ｇ／ｌ·三种培养基ｐＨ均为６。     

Two Processes Responsible for Chemiluminescence Development in the Course of Iron-Mediated Lipid Peroxidation

The kinetics of chemiluminescence (CL) accompanying Fe²⁺-induced lipid peroxidation (LPO) in liposome suspension has been investigated. A sequence of stages was observed, namely: (1) fast CL flash (FF); (2) latent period (LP); (3) slow CL flash (SF) and (4) stationary chemiluminescence (SL). The first three stages are known to reflect the Fe²⁺-mediated LPO process. In spite of the fact that at the stage of SL Fe²⁺ has completely oxidized and MDA has not accumulated, CL intensity was found to increase and after 0.5–1 h reached a value that was several times higher than SF amplitude. The maximal SL level was linearly dependent on the initial Fe²⁺ concentration and was not dependent on liposome concentration in the suspension. The nature of the processes responsible for CL emission at the stage of SL has been investigated using free radical reaction inhibitors and measurement of CL spectra. The SL spectrum was observed in the red region (λ>590 nm) in contrast to the SF CL spectrum (maximum at 540 nm). SL amplitude was strongly inhibited by sodium azide (40%), superoxide dismutase (SOD) (30%), desferrioxamine and EDTA (30%), whereas mannitol, ethanol, α-tocopherol and butylated hydroxytoluene were ineffective. The data obtained indicate that CL at the stage of SL is not directly related to LPO process, i.e. lipid free radical recombination. The mechanism of stationary CL generation is discussed.     

Lipid Peroxidation in the Presence of Albumin,Inhibitory and Prooxidative Effects

Oxidative modifications of LDL are involved in atherogenesis. Previously we have developed a simple assay to evaluate the susceptibility of lipids to copper-induced peroxidation in the relatively natural milieu of unfractionated serum in the presence of excess citrate. Based on our previous results we have proposed that the inducer of peroxidation in our optimized assay is a copper-citrate complex. Recent investigations indicate that under certain conditions a copper-albumin complex may induce peroxidation of ascorbate. Two different complexes may be formed in albumin-containing systems (e.g. serum) namely 1:1 and 2:1 copper-albumin complexes. The aim of the present work was to evaluate the possibility that at least one of these complexes may be responsible for the induction of peroxidation of lipids in lipidic systems containing copper and albumin, including our optimized assay. Towards this end, we have investigated the dependence of copper-induced peroxidation on the concentration of added albumin in lipidic systems in the absence and presence of citrate. In all the systems investigated in this study (PLPC liposomes, LDL, HDL and mixtures of HDL and LDL) we found that at low concentrations of free copper (e.g. in the presence of excess citrate) the 2:1 copper-albumin complex is redox-active and that this complex is the major contributor to the initiation of lipid peroxidation in these systems and in our optimized assay. The possible relevance of the induction of peroxidation in vivo by the latter complex has yet to be studied. <footnote id="fn1"><no>*</no>This work was performed in partial fulfillment of the requirements for a Ph.D. degree of Dorit Samocha-Bonet, Sackler Faculty of Medicine, Tel-Aviv University, Israel. </footnote>     

药用植物华泽兰组织培养和快速繁殖

通过比较不同的外植体、植物生长调节剂种类和浓度配比、生根培养基类型以及生根苗的移栽基质,建立华泽兰组织培养快速繁殖体系。结果表明,外植体表面消毒以75%酒精预处理10s,再用0.1%HgCl2浸泡10min,以嫩茎节为外植体诱导效果最好。培养基MS＋6-BA1.00mg.L-1＋IBA0.05mg.L-1利于形成丛生芽,用于继代增殖,30d的增殖系数为9.43;1/2MS＋IBA0.05~0.10mg.L-1适宜诱导生根获得再生植株,生根率100%;生根苗适宜移栽于田园土中,成活率93.3%。     

应用正交设计法优选黄独脱毒苗快繁培养基

通过正交设计法研究黄独脱毒苗的快繁培养基,考察KT、NAA和2,4-D对黄独脱毒苗快繁的影响。结果表明,黄独脱毒苗快繁的最佳培养基为MS+KT 2.0 mg/L+NAA 0.5 mg/L。     

厚皮甜瓜(Cucumis melo var. reliculatus)的快速繁殖

以厚皮甜瓜 (Cucumismelovar.reliculatus)西薄洛托带腋芽茎段为外植体进行离体快速繁殖研究。结果表明 :在MS BA 0 .5～ 1 .0mg/L IAA 0 .1mg/L的培养基上利于诱导形成丛生芽 ,芽的月增殖系数达到 1 1以上 ;在 1 /2MS IAA 0 .5mg/L培养基上并经暗处理 3d最易生根 ,生根率 90 % ;在蛭石 :草炭土 =1 :1 (体积比 )基质中移栽驯化效果好。试管植株定植大田后种性不变 ,生长和结果习性优于种子苗。     

Interactions of Nitric Oxide with Lipid Peroxidation Products under Aerobic Conditions: Inhibitory Effects on the Formation of Malondialdehyde and Related Thiobarbituric Acid-Reactive Substances

Under aerobic conditions, exposure of peroxidized lipids to nitric oxide (NO) was found to result in a rapid decrease in the levels of thiobarbituric acid-reactive substances (TBARS). Addition of 10–100 μM NO to rat brain homogenates preincubated for 2 h at 37°C caused up to a 20% decrease in the levels of TBARS compared to controls. A similar inhibitory effect was observed on TBARS produced by Fe²⁺-induced decomposition of 15-hydroperoxyeicosatetraenoic acid (15-HPETE), due apparently to NO-induced decomposition of the hydroperoxide (ferrous oxidation/xylenol orange assay). Prostaglandin G₂ (PGG₂, 35 μM), as a model bicyclic endoperoxide, and malondialdehyde (MDA, 20 μM), the main component of TBARS, proved also susceptible to degradation by NO or NO donors (diethylamine NONOate, DEA/NO) at concentrations of 100 μM or higher in 0.05 M phosphate buffer, pH 7.4, and at 37°C, as indicated by the reduced response to the TBA assay. No significant effect on TBARS determination was caused by nitrite ions. These and other data indicate that NO can inhibit TBARS formation by decomposing primary lipid peroxidation products, chiefly 15-HPETE and related hydroperoxides, and, to a lesser extent, later stage TBARS precursors, including bicyclic endoperoxides and MDA, via nitrosation and other oxidative routes, without however affecting chromogenic reactions during the assay.     

Occurrence of Lipid Peroxidation in Brain Microsomes in the Presence of NADH and Vanadate

Oxidation of NADH by rat brain microsomes was stimulated severalfold on addition of vanadate. During the reaction, vanadate was reduced, oxygen was consumed, and H2O2 was generated with a stoichiometry of 1:1 for NADH/O2, as in the case of other membranes. Extra oxygen was found to be consumed over that needed for H2O2 generation specifically when brain microsomes were used. This appears to be due to the peroxidation of lipids known to be accompanied by a large consumption of oxygen. Occurrence of lipid peroxidation in brain microsomes in the presence of NADH and vanadate has been demonstrated. This activity was obtained specifically with the polymeric form of vanadate and with NADH, and was inhibited by the divalent cations Cu2+, Mn2+, and Ca2+, by dihydroxyphenolic compounds, and by hemin in a concentration-dependent fashion. In the presence of a small concentration of vanadate, addition of an increasing concentration of Fe2+ gave increasing lipid peroxidation. After undergoing lipid peroxidation in the presence of NADH and vanadate, the binding of quinuclidinyl benzylate, a muscarinic antagonist, to brain membranes was decreased.     

Diapause Induction and Termination in Eggs of the Fruit Tree Red Spider Mite Panonychus Ulmi in Northern Greece

In apple orchards in northern Greece, females of Panonychus ulmi Koch were found to lay diapause eggs from late August to the beginning of October. The course of diapause termination in the field was determined by transferring diapause eggs during winter and early spring from apple orchards with the varieties Starkinson and Firiki to short days (LD 8:16) (1992–1996), and long days (LD 16:8) (1994–1995), both at 20 °C. Percentages of diapause termination were very low to zero from October to the beginning of January, then progressively increased throughout January and February. Diapause termination in 50% of the eggs occurred in the first half of February in lowland mite populations irrespective of the year and location from which the eggs originated, and about one month earlier in a population originating from an altitude of 300 m. For each sampling date throughout the winter, the mean number of days required for 50% egg hatch at 20 °C (T_50%) was similar under either a long (LD 16:8) or a short (LD 8:16) photoperiod. Diapause eggs collected in October 1995 from two orchards and maintained at 0, 5, 10 and 15 °C for various periods were subsequently transferred to 20 °C and LD 8:16, where TP_50% was determined. It was shown that temperature, duration of maintenance at the different temperatures and the orchard from which the eggs originated had a significant effect on T_50% and therefore on diapause development. Additionally, in our strains diapause intensity was much weaker than in strains from more northern latitudes and was terminated even without any cold exposure. The variation in diapause intensity in different strains of P. ulmi may have an adaptive significance for this widespread species.     

菊芋组织培养快繁技术的建立

以菊芋带芽点的薯盘及带节的幼嫩茎段为外植体,MS为基本培养基,附加不同种类和浓度的生长调节物质,研究菊芋组织培养和快速繁殖的技术环节,最终筛选出最优技术参数组合,建立菊芋再生体系。试验结果表明：茎段外植体是理想的快速繁殖材料,正接（形态学下端向下）是最佳的接种方式。芽诱导最佳培养基为MS＋1.0mg·L-16-BA＋0.2mg·L-1IBA,诱导率为95%;继代增殖最适宜培养基为MS＋2.0mg·L-16-BA;壮苗培养最佳培养基为MS＋0.1mg·L-16-BA;生根适宜培养基为MS＋0.2mg·L-1NAA,生根率达100%;移栽成活率达95%,大田种植成活率达95%以上。     

春石斛丛生芽组培快繁研究

本试验采用正交设计,探讨春石斛组培以丛生芽途径进行快速繁殖的方法。研究主要集中在不同基本培养基类型、不同生长调节剂配比及不同添加物等因素对丛生芽增殖的影响,从中筛选最优技术参数组合,提高丛生芽增殖系数,建立春石斛最优再生体系。结果表明：影响丛生芽增殖的显著因子分别是基本培养基、6-BA、KT;最适宜的培养基配方是1/2 MS + 6-BA 1.0 mg/L + NAA 1.0 mg/L + KT 0.5 mg/L +蔗糖30.0 g/L +琼脂7.0 g/L +椰汁150.0 ml/L,pH 5.4。此外,春石斛丛生芽增殖的外植体以1.5 cm带节茎段、接入密度每瓶3株较适宜。     

Estrogen Hormones Reduce Lipid Peroxidation in Cells and Tissues of the Central Nervous System

Effects of estrogen hormones on lipid peroxidation (LPO) were examined in rat brain homogenates (RBHs), hippocampal HT 22 cells, rat primary neocortical cultures, and human brain homogenates (HBHs). Dose-response curves indicated half-maximal effective concentrations (EC50) of 5.5 and 5.6 mM for iron-induced LPO in RBHs and HT 22 homogenates. Incubation of living rat primary neocortical cultures with iron resulted in an EC50 of 0.5 mM, whereas culture homogenates showed an EC50 of 1.2 mM. Estrogen hormones reduced LPO in all systems: In RBHs, estrone inhibited iron-induced LPO to 74.1 +/- 5.8% of control levels (17beta-estradiol: 71.3 +/- 0.1%) at a concentration of 10 microM. In hippocampal HT 22 cell homogenates, levels of LPO were reduced to 74.8 +/- 5.5% by estrone and to 47.8 +/- 6.2% by 17beta-estradiol. In living neocortical cultures, 17beta-estradiol decreased iron-induced LPO to 79.2 +/- 4.8% and increased the survival of cultured neuronal cells. Of the other steroid compounds tested (corticosterone, progesterone, testosterone), only progesterone decreased LPO in HT 22 cell homogenates. In HBHs, LPO was dose-dependently increased by iron concentrations from 2.7 to 6.0 mM. Incubation with estrogens resulted in a dose-dependent inhibition of LPO to 53.8 +/- 8.6% with 10 microM 17beta-estradiol, whereas estrone failed to affect iron-induced LPO to a significant extent. Nonestrogenic steroids, including hydrocortisol, did not show significant effects on LPO in HBHs.