肿瘤研究新视点——MGMT

MGMT作为一种重要的DNA修复酶对于保护细胞免受环境中的致癌物质和（或）化疗物引起的基因毒起着关键作用，因此在细胞对环境致癌物的易感性与肿瘤对化学药物的耐药性等研究领域，MGMT正受到越来越多研究者的关注。化疗药物作用的有限性一直是困扰肿瘤临床治疗的一大难题，许多人把希望寄托在肿瘤的早期发现与预防上，MGMT作为一种重要的DNA修复酶起着保护细胞免受基因毒的重要作用，利用这一性质，通过检测组织中MGMT的活性水平可以帮助我们预测正常细胞的突变性与肿瘤细胞的耐药性，为肿瘤的早期预防和确定化疗方案提供依据，本文综述了MGMT的一般性质、作用机制和临床意义。     

Selective effects of PHA on rat brush border hydrolases along the crypt-villus axis

Summary The mechanism of the toxicity of lectin fromPhaseolus vulgaris seeds has been investigated on rat enterocytes. Cell isolation procedures showed a selectivity in the loss of brush border hydrolases; this indicated that the microvilli blebbing was not the only mechanism of action of lectins on rat enterocytes.     

Peptides in the mammalian cardiovascular system

Summary Ample immunocytochemical evidence is now available demonstrating that several peptides are present in the mammalian cardiovascular system where they are localised to nerve fibres and myocardial cells. The neuropeptides (neuropeptide Y, calcitonin gene-related peptide, tachykinins and vasoctive intestinal polypeptide) are localised to large secretory vesicles in subpopulations of afferent or efferent nerves supplying the heart and vasculature of several mammals, including man. Although they often exert potent pharmacological effects on the tissues in which they occur their physiological significance has still to be established. They may act directly via specific receptors and/or indirectly by influencing the release and action of other cardiovascular transmitters. In marked contrast, atrial natriuretic peptide is produced by cardiac myocytes and considered to act as a circulating hormone.     

用二氧化碳电极测定霉菌537蛋白酶的活性

在霉菌５３７蛋白酶的作用下，酷蛋白发生水解，生成酪氨酸和谷氨酸等组成该蛋白的氨基酸，加入Ｌ－谷氨酸脱羧酶使谷氨酸发生脱羧反应，会释放出ＣＯ２，后者可用ＣＯ２电极进行测定，从而可间接地算出５３７蛋白酶的活性，在蛋白酶活性为２０００－１０００单位范围内，电位的变化值与活性呈现良好的线性关系。     

柚皮苷对DSS诱导结肠炎小鼠肠道菌群的影响

目的 探究柚皮苷( Naringin,NG)对 DSS 诱导的结肠炎小鼠肠道菌群的影响。 方法 用 C57BL / 6 雄性小鼠构建动物模型,将 15 只小鼠分为对照组、模型组和 NG 组,每组 5 只。 除对照组外,其它两组给予 4% ( m / v) DSS 自由饮用,第 2 天给予 NG 组小鼠 NG 干预。 第 9 天处死小鼠,留取结肠和粪便。 Western blot 检测炎症分子蛋白磷酸化核因子-κB-p65( p-NF-κB-p65)和凋亡蛋白 Bcl-2。 PCR-变性梯度凝胶电泳( PCR-DGGE) 技术分析小鼠肠道菌群结构。 结果 模型组 p-NF-κB-p65 和 Bcl-2 蛋白表达与对照组比较,有显著差异( P<0. 01) ,且 NG 干预后有不同程度的改变;对 PCR-DGGE 中的条带通过非加权成对算术平均( UPGMA)算法进行聚类分析,结果显示各组小鼠结肠菌群结构具有显著差异。 结论 NG 可以有效改善 DSS 诱导的结肠炎症状,改善小鼠肠道菌群。     

Sex pheromone conversion and degradation in antennae of the silkworm mothBombyx mori L.

Summary In living antennae of the silkworm mothBombyx mori L. the pheromone compound (E, Z)-10,12-hexadecadienol and hexadecanol are enzymatically converted to their corresponding fatty aldehydes, acids and long-chain fatty acid esters. The pheromone is completely degraded at high rates in the antennae of freshly hatched moths. The polar volatile [³H]metabolites exclusively consist of tritiated water. The half-life of the pheromone is about 2.5 min in males and 0.5 min in females. Drying inactivates the enzymes responsible for pheromone oxidation.Dedicated to Professor Adolf Butenandt on the occasion of his 85th birthday     

黑曲霉果胶酶的研究 Ⅱ.诱变菌株607的产酶条件实验

对诱变菌株607果胶酶的产生条件进行了试验,酶活性水平为3000u/g 以上。     

Mitochondrial abnormalities in fibroblast line GM3093 defective in oxidative metabolism

Summary Fibroblast line GM3093 deficient in the activity of the pyruvate dehydrogenase complex, was derived from a patient reported to have an inherited defect affecting the tricarboxylic acid cycle. Our results suggest a generalized defect consisting of few and abnormal mitochondria and low activities of all mitochondrial enzymes examined.Preliminary reports of aspects of this work appeared as abstracts in Trans. Am. Soc. Neurochem.15 (1984) 178, and Soc. Neurosci.10 (1984) 996.Developmental and Metabolic Neurology Branch.Surgical Neurology Branch.     

Heparan sulfate-protein interactions: therapeutic potential through structure-function insights

Heparin and the related glycosaminoglycan, heparan sulfate, bind a myriad of proteins. The structural diversity of heparin and heparan sulfates is enormous, but differences in the conformational flexibility of the monosaccharide constituents add extra complexity and may influence protein binding. Silencing genes for heparin/ heparan sulfate biosynthetic enzymes profoundly affects mammalian development. Thus, altering the structure of heparan sulfate chains can alter protein binding and embryo development. Different heparan sulfate structures are located in particular tissue sites, and these structures are recognised by different sets of proteins. Regulation of certain heparan sulfate-protein interactions by pH or cations is described. Heparin/heparan sulfate structures are viewed as potential therapeutics for a variety of diseases. An understanding at the molecular and functional levels of the specificity and affinity of heparan sulfate-protein interactions is crucial for designing heparin-inspired drugs. How the development of synthesis techniques is facilitating structure-function analyses and drug development is discussed.Received 6 July 2004; received after revision 16 September 2004; accepted 28 September 2004     

Enzymology of NAD+ homeostasis in man

This review describes the enzymes involved in human pyridine nucleotide metabolism starting with a detailed consideration of their major kinetic, molecular and structural properties. The presentation encompasses all the reactions starting from the de novo pyridine ring formation and leading to nicotinamide adenine dinucleotide (NAD⁺) synthesis and utilization. The regulation of NAD⁺ homeostasis with respect to the physiological role played by the enzymes both utilizing NAD⁺ through the nonredox NAD⁺-dependent reactions and catalyzing the recycling of the common product, nicotinamide, is discussed. The salient features of other enzymes such as NAD⁺ pyrophosphatase, nicotinamide mononucleotide 5-nucleotidase, nicotinamide riboside kinase and nicotinamide riboside phosphorylase, described under miscellaneous, are likewise presented.Received 30 April 2003; received after revision 9 June 2003; accepted 20 June 2003