Role of deubiquitinating enzymes in DNA double-strand break repair

DNA is the hereditary material in humans and almost all other organisms. It is essential for maintaining accurate transmission of genetic information. In the life cycle, DNA replication, cell division, or genome damage, including that caused by endogenous and exogenous agents, may cause DNA aberrations. Of all forms of DNA damage, DNA double-strand breaks(DSBs) are the most serious. If the repair function is defective, DNA damage may cause gene mutation, genome instability, and cell chromosome loss, which in turn can even lead to tumorigenesis. DNA damage can be repaired through multiple mechanisms. Homologous recombination(HR) and non-homologous end joining(NHEJ) are the two main repair mechanisms for DNA DSBs. Increasing amounts of evidence reveal that protein modifications play an essential role in DNA damage repair.Protein deubiquitination is a vital post-translational modification which removes ubiquitin molecules or polyubiquitinated chains from substrates in order to reverse the ubiquitination reaction. This review discusses the role of deubiquitinating enzymes(DUBs) in repairing DNA DSBs. Exploring the molecular mechanisms of DUB regulation in DSB repair will provide new insights to combat human diseases and develop novel therapeutic approaches.     

贵州果柚汁对肝脏氧化酶活性的影响

用不同方法给大白鼠注入贵州果柚汁,结果表明：单次和多次摄取果柚汁对肝脏氧化酶活性有不同程度的影响。两种处理方法都使谷胱苷肽含量发生明显变化,而对过氧化氢酶活性均无明显影响。     

Antioxidant effect of methanolic extract of<Emphasis Type="Italic">Solanum nigrum</Emphasis> berries on aspirin induced gastric mucosal injury

The antiulcerogenic effects of the methanolic extract ofSolanum nigrum berries (SBE) on aspirin induced ulceration in rats with respect to antioxidant status in the gastric mucosa have been investigated. Oxygen free radicals are considered to be important factors in the pathogenesis of gastric ulcer. The level of lipid peroxides, which were elevated highly in rats with acute gastric mucosal injury was taken as an index of oxidative stress. The activities of antioxidant defense enzymes were also decreased considerably by oral gastric administration of aspirin. The decreased levels of antioxidant enzymes and increased mucosal injury were altered to near normal status upon pretreatment with (SBE) when compared to the ulcer induced rats. The results indicate that (SBE) may exert its gastroprotective effect by a free radical scavenging action. Our observations suggest that (SBE) may have considerable therapeutic potential in the treatment of gastric diseases.     

Effect of vitamin E on platelet enzymatic anti-oxidants in the patients of myocardial infarction

Effect of administration of 600 mg. vitamin E each day, for six days, was observed on activity of some of the anti-oxidant enzymes and levels of malondialdehyde (as an index of free radical mediated damage) in the platelets of patients reperfused after myocardial infarction. It has been found that vitamin E administration significantly lowers the level of malondialdehyde in the patients. Vitamin E administration increases the activities of anti oxidant enzymes (viz. superoxide dismutase, glutathione reductase and catalase) tested both in the patients and healthy controls. Vitamin E administration causes general stimulation of anti-oxidant enzyme activities both in healthy persons and the patients, however, lowering of lipid per-oxidation upon administration of vitamin E is specific for patients. These findings exhibit beneficial role of vitamin E administration in the management of the patients reperfused after myocardial infarction.     

Evaluation of the radioprotective effect of turmeric extract and vitamin E in mice exposed to therapeutic dose of radioiodine

The aim of this study was to evaluate the radioprotective effect of turmeric extract (40 mg/kg body weight) and vitamin E (α- tocopherol acetate, 400 IU/kg body weight) supplementation on lipid peroxidation, reduced glutathione and antioxidant defense enzymes in various organs like liver, kidney and salivary glands at 24 h in adult Swiss mice. ¹³¹Iodine exposure significantly increased lipid peroxidation in kidney and salivary glands in comparison to control animals. Pre supplementation with turmeric extract for 15 days showed significant lowering of lipid peroxidation in kidney. On the other hand vitamin E pre supplementation showed marked reduction in lipid peroxidation in salivary glands. Reduced glutathione levels decreased significantly in liver after radiation exposure. However, pre supplementation with turmeric extract and vitamin E did not improve glutathione levels in liver. In conclusion, we have observed differential radioprotective effect of turmeric extract and vitamin E in kidney and salivary glands. However, Vitamin E seems to offer better radioprotection for salivary glands which is known to be the major site of cellular destruction after radioiodine therapy in patients.     

不同产地大蒜抗氧化性能的研究

对不同产地大蒜抗氧化性能进行测定.亚铜离子和过氧化氢反应产生羟基自由基,当加入大蒜时,羟基自由基和水杨酸反应产物荧光强度发生变化,用荧光分光光度法测定大蒜对羟基自由基的清除率的方法.得出不同产地大蒜均具有一定的抗氧化性能,大蒜抗氧化性能因产地不同而不同的结论.     

间歇运动训练和急性间歇运动对缺血/再灌注大鼠心电图及血清心肌酶的影响

目的:探索长期运动训练和急性运动的心脏保护作用及心电指标的变化规律,为进一步研究运动预适应机制提供依据.方法:32只3月龄雌性SD大鼠随机分成3大组:间训模型组(n=8)、急性运动模型组和对照组(n=8),间歇运动训练组进行高强度间歇运动训练,急性间歇运动组仅进行急性高强度的间歇运动,对照组(n=16)不运动,在心脏模型制备时对照组随机分成对照模型组(n=8)和对照假手术组(n=8).运动训练结束后,各组大鼠均采用结扎左冠状动脉制备在体大鼠心肌缺血/再灌注损伤模型,但对照假手术组只开胸穿线而不结扎.缺血/再灌注过程实行全程心电监控,缺血30 min、再灌注40 min后,测定血清心肌酶.结果:经间歇运动训练和急性间歇运动处理的缺血/再灌注大鼠血清心肌酶明显低于对照模型组(P<0.05或P<0.01);缺血30 min及再灌注40 min间歇运动训练组心电图ST段、T波面积和QT间期明显低于对照模型组(P<0.05或P<0.01);再灌注40min急性间歇运动组心电图ST段、T波和QT间期明显低于对照模型组(P<0.05).结论:长期间歇运动训练产生心肌抗缺血/再灌注损伤的保护作用,急性运动主要产生抗心脏再灌注损伤的保护作用.     

昆虫壳聚糖对运动训练大鼠肝脏抗氧化酶系与SOD基因表达的影响

目的:报道了补充虫源壳聚糖对大鼠肝脏抗氧化酶系和SOD基因表达影响的研究结果。方法:对大负荷游泳训练大鼠补充剂量分别为各组平均体重的0.5 g/kg、1.0 g/kg和2.0 g/kg的虫源壳聚糖,在8周大负荷训练结束后测定肝脏抗氧化酶系的活性,并分析不同处理组动物肝脏SOD基因表达水平差异。结果:补充虫源壳聚糖能够显著提高抗氧化酶系活性,虫源壳聚糖0.5 g/kg补充组与单纯大负荷运动组相比,SOD、CAT和GSH-Px酶活性显著升高(P<0.05);虫源壳聚糖1.0 g/kg和2.0 g/kg补充组与单纯大负荷运动组相比:SOD、CAT和GSH-Px酶活性升高极为显著(P<0.01)。MDA含量在不同水平虫源壳聚糖补充组均显著低于单纯大负荷运动组(P<0.01)。对SOD基因表达分析结果显示,SOD酶活性的升高与其基因表达水平提高呈正相关。结论:补充虫源壳聚糖有助于提高训练大鼠的运动肝脏抗氧化酶系活性,活性的提高与相关编码基因的表达水平提高有关。     

香根草提取物对二化螟生长发育及体内保护酶活力的影响

将香根草地上部分不同极性溶剂(石油醚、乙酸乙酯、正丁醇和水)的提取物加入到人工饲料中喂食二化螟幼虫,进行了提取物对二化螟初孵幼虫的毒杀作用、三龄幼虫的生长发育抑制作用及其体内保护酶(POD,SOD和CAT)活性影响的测定分析。结果表明,不同溶剂的提取物(0.01 g/m L)对二化螟幼虫均有毒杀作用,其作用大小排序为石油醚乙酸乙酯正丁醇水,其中石油醚提取物处理3 d后二化螟初孵幼虫存活率为15.8%,5 d后存活率为0.8%。三龄幼虫取食添加了不同提取物(0.05 g/ml)的人工饲料7 d后,生长发育均得到明显抑制,以石油醚和乙酸乙酯提取物作用最强,生长发育抑制率分别达111.11%和109.50%;同时,三龄幼虫体内的SOD活力明显高于对照,CAT和POD活力明显低于对照,其中石油醚和乙酸乙酯提取物和对照差异均达显著水平。研究表明香根草中含对二化螟幼虫有毒杀和生长发育抑制作用的活性物质,以石油醚和乙酸乙酯提取物中最为丰富。香根草提取物扰乱了二化螟幼虫体内保护酶SOD、CAT和POD的动态平衡,使虫体内自由基的清除遇到障碍,从而对其产生毒害作用。     

杜仲提取物对大鼠运动能力的营养干预研究

探讨杜仲提取物(Eucommia ulmoides Oliver extract,EUOE)对大鼠运动能力的营养干预,为EUOAE在运动营养干预中的应用提供实验依据。SD雄性大鼠24只,体重180-220 g,随机分为安静对照组8只、运动训练组8只、运动+EUOE 8只。在最后一次训练后,安静对照组不进行力竭运动训练取材,运动训练组、运动+EUOAE组进行力竭运动,测定其运动至力竭的时间后取材,测定骨骼肌与抗氧化水平相关的生物化学指标。研究结果表明,EUOE可以提高运动训练大鼠骨骼肌抗氧化酶活性、ATPase活性和GSH含量,降低骨骼肌MDA含量和血清LDH、CK活性,延长大鼠跑台运动至力竭时间,具有抗疲劳作用。