基于MLS卫星临边探测数据研究大气OH时空分布

 OH自由基是大气中重要的氧化剂,对大气中其他气体成分和气溶胶的形成和转化起着重要作用。本文利用MLS(micro-wave limb sounder)卫星观测资料,对大气平流层上层和中间层OH自由基的时空分布和变化以及中国上空OH自由基的垂直分布进行分析。结果显示,大气平流层上层和中间层OH自由基含量存在明显的季节变化和昼夜变化,在空间上的分布也随着太阳直射点的不同而呈现一定的周期性。比较了中国上空与同纬度纬向平均值,发现白天和夜间的观测值只有个别位置有较明显偏差,中国地区上空的OH含量比在整体上与同纬度比起来无明显异常,中国局地上空廓线的比较更加详细地反映了OH自由基的昼夜垂直结构。总之,中层大气OH自由基含量存在显著的昼夜变化、季节变化,同时也受太阳活动的影响,年际变化则不明显。     

蚯蚓冻干粉的抗氧化作用

为了探讨蚯蚓冻干粉的体内外抗氧化活性,取60只小鼠,随机分为5组,空白对照组饲喂基础饲料,高脂饲料组饲喂高脂饲料,其余3组在饲喂高脂饲料的同时按0.6,0.4,0.2 g/kg体重灌胃蚯蚓冻干粉悬液.8周后,断尾采血测定血清中超氧化物歧化酶(SOD)活性和丙二醛(MDA)含量;体外采用邻苯三酚反应系统产生超氧阴离子(O2-),过氧化氢反应体系产生羟基自由基(OH-),检测不同浓度蚯蚓冻干粉悬液上清对自由基的清除作用.结果表明:血清中MDA的含量和SOD活力显著降低(p0.01);蚯蚓冻干粉悬液在实验质量浓度(0.06 g/mL)时对超氧阴离子有显著的清除作用,清除率为23.9%,对羟基自由基的抑制率可达94.6%.     

岩白菜素清除小鼠脑组织自由基及抗脂质过氧化作用

目的:研究岩白菜素对小鼠脑组织缺血再灌注的保护作用。方法:通过测定小鼠正常脑组织和缺血再灌注脑组织分别与岩白菜素作用后生成脂质过氧化产物及通过比色法测定岩白菜素对黄嘌呤-黄嘌呤氧化酶体系产生的超氧阴离子自由基的清除作用,评价岩白菜素对脑的保护作用。结果:岩白菜素能有效地抑制缺血后脑组织发生的脂质过氧化反应,对黄嘌呤-黄嘌呤氧化酶体系产生的超氧阴离子自由基也有明显的清除作用。结论:岩白菜素对小鼠脑缺血再灌注损伤有一定的保护作用。     

不同剂型生脉散对氧自由基清除作用的比较

研究了生脉注射液、生脉饮、生脉胶囊这3种直接用于临床的成药剂型是否也具有抗氧自由基（羟自由基·OH和超氧阴离子自由基O－2·）作用,并且不同剂型之间是否有差异.用邻二氮菲-Fe2+氧化法测定·OH,用改进的邻苯三酚自氧化法测定O－2·.结果表明,3种剂型生脉散均有清除·OH和O－2·的能力,与对照管比较有高度显著性差异（P＜0.01）,各剂型之间无显著性差异（P＞0.05）.     

TDI对靶器官的自由基损伤作用

为了揭示环境污染物甲苯二异氰酸酯(toluenediisocyanate,简称TDI)的毒性作用机制,采用静式吸入染毒从自由基损伤的角度观察了TDI对靶器官的超氧化物歧化酶(SOD)、丙二醛(MDA)、谷胱甘肽(GSH)和一氧化氮(NO)的影响。结果表明,TDI可引起肺脏和睾丸的中MDA、NO含量增加,GSH和SOD在肺组织和睾丸组织中均有消耗,表明TDI可导致肺脏和睾丸内氧自由基(O2.)和一氧化氮自由基(NO.)的增多。提示:呼吸道接触TDI可引起靶器官的自由基损伤,研究结果为该环境污染物的预防和早期诊断提供实验基础。     

BCK-代数根理论的若干结果

本文讨论了BCK-代数类所确定的下根结构以及根格中诸如交根、并根等问题,证明了单遗传类与遗传类所确定的下根分别是单遗传根和遗传根。     

稳定根格和线性半素(p∶q)根格的原子

本文讨论了稳定根格以及线性半素(p:q)根格的原子的一些问题.证明了线性半素(p:q)根格是原子格,它的每一个原子的形式是(px+1:1).这里p是一个素数.     

Tissue protection against oxidative stress

We used an enhanced luminescence technique to study the response of rat tissues, such as liver, heart, muscle and blood, to oxidative stress and to determine their antioxidant capacity. As previously found for liver homogenate, the intensity of light emission (E) of tissue homogenates and blood samples, stressed with sodium perborate, is dependent on concentration, and the dose-response curves can be described by the equation E=a·C/exp(b·C). Theb value depends on the antioxidant defence capability of the tissues. In fact, it increases when homogenates are supplemented with an antioxidant, and is correlated with tissue antioxidant capacity, evaluated by two previously set up methods both using the same luminescence technique. Our results indicate that the order of antioxidant capacity of the tissues is liver>blood>heart>muscle. Thea value depends on the systems catalysing the production of radical species. In fact, it is related to the tissue level of hemoproteins, which are known to act as catalysts in radical production from hydroperoxides. The equation proposed to describe the dose-response relation is simple to handle and permits an immediate connection with the two characteristics of the systems analysed which determine their response to the pro-oxidant treatment. However, the equation which best describes the above relation for all the tissues is the following: E=·C/exp(·C). The parameter assumes values smaller than 1, which seem to depend on relative amounts of tissue hemoproteins and antioxidants. The extension of the analysis to mitochondria shows that they respond to oxidative stress in a way analogous to the tissues, and that the adherence of the dose-response curve to the course predicted from the equation E=a·C/exp(b·C) is again dependent on hemoprotein content.     

A new cellular function for peroxisomes related to oxygen free radicals?

Summary Although in cell biology peroxisomes are still young organelles, it is becoming increasingly clear that they are involved in important cellular functions. Recent results have indicated the presence of the metalloenzyme superoxide dismutase in peroxisomes and the production of superoxide free radicals (O ₂ ^– ) in these oxidative organelles. These findings, together with other experimental evidence, point towards the existence of new roles for peroxisomes in cellular active oxygen metabolism, something that has a potential impact in multiple areas of cell biology, particularly in biochemistry and biomedicine.     

Biochemical aspects of radiation biology

Summary In order to analyze the mechanisms of biological radiation effects, the events after radiation energy absorption in irradiated organisms have to be studied by physico-chemical and biochemical methods. The radiation effects in vitro on biomolecules, especially DNA, are described, as well as their alterations in irradiated cells. Whereas in vitro, in aqueous solution, predominantly OH radicals are effective and lead to damage in single moieties of the DNA, in vivo the direct absorption of radiation energy leads to locally multiply-damaged sites, which produce DNA double-strand breaks and locally denatured regions. DNA damage will be repaired in irradiated cells. Error free repair leads to the original nucleotide sequence in the genome by excision or by recombination. Error prone repair (mutagenic repair), leads to mutation. However, the biochemistry of these processes, regulated by a number of genes, is poorly understood. In addition, more complex reactions, such as gene amplification and transposition of mobile gene elements, are responsible for mutation or malignant transformation.