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.     

盐酸兰地洛尔原料药中3-[4-(3-硝基苯磺酰氧基)苯基]丙酸的检测方法学研究

为了检测并控制合成盐酸兰地洛尔原料药物的质量,依托高效液相色谱-三重串联四级杆质谱建立了一种测定其中痕量基因毒性杂质3-[4-(3-硝基苯磺酰氧基)苯基]丙酸的方法。方法采用多级反应监测模式,检测灵敏度可达到0.50 mg/kg,加标回收率在91.9%~97.8%之间,且精密度的相对标准偏差为3.28%(n=6),均能满足杂质检测的需要。该研究方法操作简单、结果可靠,可实现快速、低成本检测。     

快速电子辐照F—40自由基的ESR定量方法

本文介绍了带固定内标的ESR定量测量自由基浓度的原理，简述了采用CuSO4·5H2O单晶作为固定内标，采用DPPH作为工作标样测量快速电子辐照F-40材料中残存自由基浓度方法。     

硫醇催化的醛类化合物加成至烯酰胺类化合物的自由基链反应(英文)

伯醛化合物加成在富电子碳碳双键的自由基链反应可以通过硫醇的催化作用来实现，硫醇的作用表现为一个极性可逆的催化剂，它可以促使氢原子从醛完全转移至加成自由基上，该自由基是载链酰基自由基加成至烯酰胺上所生成的     

Nitric oxide: a radical molecule in quest of free radicals in proteins

A number of enzymes use an amino acid free radical cofactor. Tyrosyl and tryptophanyl radicals react with nitric oxide (NO) with an almost diffusion-limited rate. The catalytically competent tyrosyl radical in ribonucleotide reductase (RR) and prostaglandin H synthase (PGHS) recombines with NO in a radical-radical reaction. The unstable adduct formed can dissociate to regenerate the tyrosyl radical. However, upon prolonged incubation with NO, the diiron center of mouse RR leaks out, while the adduct is sucessively oxidized into an iminoxyl radical and a nitrotyrosine in PGHS. These data provide a plausible mechanism for the physiological inactivation of RR observed in various models, and may help in understanding the inhibition of PGHS reported in some cases. Reversible combination with NO is an intrinsic property of tyrosyl radicals, which also occurs with Y_D ^• and Y_Z ^• in photosystem II, where NO has been useful in the analysis of the oxygen-evolving complex.     

枸杞对小鼠急性运动后自由基代谢的影响

50只昆明种雄小鼠,随机分为对照组（G1）,急性运动组（G2）,急性运动＋枸杞组（G3）,力竭运动组（G4）,力竭运动＋枸杞组（G5）。对实验运动喂养2周后进行负重游泳,测定血液和线粒体某些生化指标的变化。结果显示：枸杞有增加小鼠游泳耐力时间的作用（P＜0．01）;急性运动后G3组RBC及心肌线粒体GSH－Px活力明显高于G2组（P＜0．05）;力竭24小时后,G5组RBC及心肌线粒体、血浆MDA含量明显低于G4组（P＜0．05）。结果表明,枸杞可以通过抗自由基损伤,对抗运动性疲劳。     

Spectroscopic calculation of asymmetric top free radicals: method and program

This paper sketches out the effective Hamiltonian and basis set adopted in the spectroscopic calcula tion of asymmetric top free radicals, and details the machine implementation of the spectral analysis of asymmetric top free radicals, the design and usage of the program package. To demonstrate the application of this program, analyses have been performed on the far infrared laser magnetic resonance spectrum of 14N16O2( I = 1) and the infrared diode laser spectrum of the v3 band of PO2( I = 1/2) using the program.     

食品体外抗氧化能力评价方法探讨

食品抗氧化能力评价是功能性食品研究的重要领域.目前体外抗氧化能力评价存在着定义不清,实验方法混乱等方面的问题,极大地阻碍了人们比较和筛选抗氧化功能性食品.因此,开发一种能准确评价样品抗氧化能力的方法是亟待解决的世界性难题.从诱导方式,反应机理,结果指标等角度讨论主要体外化学抗氧化评价方法和体外细胞抗氧化评价方法的特点以及他们的缺陷,并对体外抗氧化评价方法的发展与创新提出了展望.     

无声放电场中OH自由基发生及其氧化碳烟的动力学模拟

在实验研究声声放电作用于Ｎ２－Ｈ２Ｏ简单介质而发生ＯＨ自由基，并给出基本定量结果的基础上，建立电子碰撞模型和单元反应方程组，模拟无声放电场中ＯＨ自由基发生及其氧化碳烟的动力学过程，计算结果与实验数据相吻合。确认ＯＨ自由基在碳烟氧化过程中的关键作用和对其进行动力学模拟的可行性。     

Physiological and nutritional importance of selenium

Summary The essential trace element selenium has recently attracted attention because of its potentialities in the maintenance of human health. Selenium forms part of the active site of the peroxide-destroying enzyme glutathione peroxidase, and it also has other functions, for example in biotransformation, detoxification and the immune response. Functional and clinical consequences of selenium deficiency states have been described, and the selenium requirement, which is influenced by the usual selenium exposure, has been discussed. Wide variations have been found in selenium status in different parts of the world, and populations or groups of patients exposed to marginal deficiency are more numerous than was previously thought.Current research activities in the field of human medicine and nutrition are devoted to the possibilities of using selenium for the prevention or treatment of degenerative or free radical diseases such as neurological disorders, inflammatory diseases or cancer. Pharmacological selenium doses are also recommended as an adjuvant in some treatments.