血清晚期氧化蛋白产物与2型糖尿病合并冠状动脉病变的相关性研究

为了研究血清晚期氧化蛋白产物与2型糖尿病患者冠状动脉病变并发症的相关性。本研究选择50例2型糖尿病患者和30例健康体检者,取血后用分光光度法测定血清中晚期氧化蛋白产物的含量,使用全自动生化分析仪检测空腹血糖、总胆固醇和甘油三酯水平,使用微柱亲和层析法测定糖化血红蛋白的含量。研究显示血清晚期氧化蛋白产物在2型糖尿病组中的含量显著高于健康体检者组(p0.05);在血糖控制不良组中显著高于血糖控制良好组(p0.05)。2型糖尿病高晚期氧化蛋白产物患者组的空腹血糖、总胆固醇、甘油三酯和糖化血红蛋白水平显著高于低晚期氧化蛋白产物患者组(p0.05)。单因素相关分析显示血清晚期氧化蛋白产物与空腹血糖、总胆固醇、甘油三酯、糖化血红蛋白水平正相关。2型糖尿病患者中,患有冠状动脉病变并发症的患者血清晚期氧化蛋白产物水平显著高于非冠状动脉病变并发症患者(p0.05)。Logistic回归分析显示年龄、平均动脉压和AOPP的水平是2型糖尿病患者冠状动脉病变并发症发生的独立危险因素。本研究表明2型糖尿病患者体内氧化应激反应增强,血清晚期氧化蛋白产物水平升高,与冠状动脉病变并发症密切相关。     

四氧嘧啶致大鼠糖尿病与脂类过氧化

四氧嘧啶致SD大白鼠糖尿病的过程中,首先引起体内多种组织器官广泛发生脂类过氧化作用。脂类过氧化物分解产生一些醛类物质,故血清、胰腺、肝和肾组织中TBA反应物(主要成分为丙二醛)含量升高;生成的其它醛类物质与蛋白质结合形成的水溶性荧光物质含量亦增多。抗氧化剂维生素E的抗脂类过氧化作用对机体起保护作用;而维生素C在大量氧化剂四氧嘧啶存在的条件下起氧化强化剂的作用,并使机体对维生素E的消耗增多。     

非酶糖化反应与衰老

非酶糖化反应与衰老孙贺英,张宗玉（北京医科大学生化与分子生物学系,北京１０００８３）关键词非酶糖化,衰老近年发现,蛋白质、ＤＮＡ与还原糖之间形成的非酶促糖化产物不仅在糖尿病患者中增高,在老年人体内也明显增加。这些糖化产物经氧化反应进一步与蛋白质、脂类...     

晚期糖基化终产物在糖尿病肾病中的病理作用

高糖环境下体内积聚的晚期糖基化终产物(advanced glycation end products,AGEs)是糖尿病慢性并发症的主要致病因素.AGEs可通过对蛋白的修饰直接作用于机体或通过受体介导的作用影响机体.本文就AGEs的来源、病理生理作用,尤其是在糖尿病肾病(diabetic nephropathy,DN)发生发展中的作用及治疗干预作一综述.     

抗氧化剂在糖尿病中的应用研究进展

氧化应激是自由基的促氧化与机体的抗氧化失衡造成的.自由基的高反应活性可以使细胞组分发生化学变化,并导致脂质过氧化.越来越多的证据表明:糖尿病患者体内活性氧物质明显增多,并且抗氧化防御系统功能紊乱.抗氧化剂可以降低糖尿病患者体内的氧化应激水平,清除自由基并改善抗氧化防御体系,所以将抗氧化剂应用于糖尿病是可行的.许多抗氧化剂已经用于糖尿病的研究与治疗,本文主要将作用于糖尿病的各种抗氧化剂做一综述.     

综述:羰基应激与衰老机理及阿尔茨海默病早期分子病因

本文从人体衰老过程中重要的共性生化过程——羰基应激——的角度出发,探讨老年性痴呆,主要指阿尔茨海默病(AD),发生发展的早期分子病因．首先,讨论与脂类、碳水化合物和蛋白质自由基氧化(氧应激)和非酶糖基化(糖应激)产生的羰基毒化作用相关的化学反应．接着,列举活性羰基在AD患者体内存在的证据并探究这些羰基毒素对细胞结构与功能的影响．最后,分析和归纳脑组织中针对羰基毒化的解毒机理,进而探讨寻找基于该机理防治AD以至抵御衰老、疲劳、亚健康的方法与途径．     

铁与2型糖尿病发病的最新进展

糖尿病对人类健康的威胁日益加重,近年来大量的实验、临床及流行病学资料显示体内铁过载与糖尿病发生存在密切关联。作为机体必需的营养元素,铁在机体组织中的稳态平衡对维持正常的生理功能至关重要。同时铁还是一种极强的促氧化剂,机体铁含量升高往往导致氧化压力增强,进而加大罹患2型糖尿病的风险;膳食中血红素铁摄入量增加以及机体铁代谢紊乱都可能导致2型糖尿病及其并发症发生。此外,其他胰岛素抵抗疾病如代谢综合征、妊娠糖尿病以及多囊卵巢综合征都与铁过载呈显著关联,过量铁是诱发这些疾病的主要原因,并直接导致胰岛素抵抗。治疗中可通过铁螯合剂的使用来有效降低机体铁水平,并改善胰岛素抵抗。这些研究成果为2型糖尿病的干预治疗提供了新思路。对铁代谢与2型糖尿病及其并发症的最新研究做简要综述。     

检测人老化胎盘组织中miR-182的表达

目的：通过检测miR-182在正常妊娠各期、老化胎盘组织中的表达,探讨miR-182在胎盘发育过程中的调控作用,并同时探讨miR-182与血管内皮生长因子（VEGF）蛋白表达的相关性,为寻找胎盘老化特别是胎盘提前老化发生机制提供依据。方法：采用实时荧光定量PCR方法检测42例标本（早孕绒毛和胎盘组织）中miR-182的表达情况。结果：miR-182在正常妊娠早孕绒毛组织、正常妊娠胎盘组织及老化胎盘组织中均表达。miR-182表达水平各个组间比较：早期与中期妊娠组、中期与晚期未足月妊娠组、晚期未足月与晚期足月妊娠组有显著差异（P〈0.05）;胎盘老化组与正常妊娠早期、中期、晚期未足月、晚期足月组有极显著差异（P〈0.01）;妊娠的早期、中期、晚期,miR-182的表达逐渐增多,老化胎盘组织中miR-182高水平表达。结论：miR-182与胎盘老化的发生高度相关,可能在胎盘老化机制中起重要的调控作用。     

晚期糖基化终末产物与糖尿病血管并发症

晚期糖基化终末产物（AGEs）是蛋白质、脂质、核酸等大分子物质的氨基基团与葡萄糖或其他还原糖的醛基在非酶促条件下发生一系列反应生成的稳定的共价加成物。晚期糖基化终末产物（AGEs）通过直接修饰蛋白质、脂质、核酸等或者与其受体相互作用的方式诱导氧化应激反应,引起机体各类细胞发生增生、炎症、纤维化反应、形成血栓等,进而加速人体的衰老或导致多种慢性退化型疾病的发生。本文从糖尿病血管并发症的角度对晚期糖基化终末产物的形成过程、致病机制等予以综述。     

吡哆胺-一种天然的AGEs/ALEs抑制剂

衰老及老年相关疾病,如：糖尿病、动脉粥状硬化、各种神经退行性疾病等,与组织蛋白氧化修饰密切相关．在造成蛋白质氧化修饰的反应中,非酶糖基化和脂质过氧化是最重要的两类,它们最终形成非酶糖基化终产物(AGEs)和脂过氧化终产物(ALEs)．基于羰基毒害衰老理论,具有强烈反应活性的羰基类化合物是非酶糖基化和脂质过氧化的共同中间产物,它们是造成蛋白修饰的直接原因之一．吡哆胺是维生素B6的一种天然成分;由于它能直接清除羰基类化合物,从而抑制AGEs／ALEs的生成;又因为吡哆胺对人体副作用很小．因此吡哆胺有望成为一种新型的防治多种老年相关疾病的药物．     

In vivo ROS production and use of oxidative stress-derived biomarkers to detect the onset of diseases such as Alzheimer’s disease,Parkinson’s disease,and diabetes

Breakthroughs in biochemistry have furthered our understanding of the onset and progression of various diseases, and have advanced the development of new therapeutics. Oxidative stress and reactive oxygen species (ROS) are ubiquitous in biological systems. ROS can be formed non-enzymatically by chemical, photochemical and electron transfer reactions, or as the byproducts of endogenous enzymatic reactions, phagocytosis, and inflammation. Imbalances in ROS homeostasis, caused by impairments in antioxidant enzymes or non-enzymatic antioxidant networks, increase oxidative stress, leading to the deleterious oxidation and chemical modification of biomacromolecules such as lipids, DNA, and proteins. While many ROS are intracellular signaling messengers and most products of oxidative metabolisms are beneficial for normal cellular function, the elevation of ROS levels by light, hyperglycemia, peroxisomes, and certain enzymes causes oxidative stress-sensitive signaling, toxicity, oncogenesis, neurodegenerative diseases, and diabetes. Although the underlying mechanisms of these diseases are manifold, oxidative stress caused by ROS is a major contributing factor in their onset. This review summarizes the relationship between ROS and oxidative stress, with special reference to recent advancements in the detection of biomarkers related to oxidative stress. Further, we will introduce biomarkers for the early detection of neurodegenerative diseases and diabetes, with a focus on our recent work.     

Glycoxidation and lipoxidation in atherogenesis

Atherosclerosis may be viewed as an age-related disease initiated by nonenzymatic, chemical reactions in a biological system. The peroxidation of lipids in lipoproteins in the vascular wall leads to local production of reactive carbonyl species that mediate recruitment of macrophages, cellular activation and proliferation, and chemical modification of vascular proteins by advanced lipoxidation end-products (ALEs). The ALEs and their precursors affect the structure and function of the vascular wall, setting the stage for atherogenesis. The increased risk for atherosclerosis in diabetes may result from additional carbonyl production from carbohydrates and additional chemical modification of proteins by advanced glycation end-products (AGEs). Failure to maintain homeostasis and the increase in oxidizable substrate (lipid) alone, rather than oxidative stress, is the likely source of the increase in reactive carbonyl precursors and the resultant ALEs and AGEs in atherosclerosis. Nucleophilic AGE-inhibitors, such as aminoguanidine and pyridoxamine, which trap reactive carbonyls and inhibit the formation of AGEs in diabetes, also trap bioactive lipids and precursors of ALEs in atherosclerosis. These drugs should be effective in retarding the development of atherosclerosis, even in nondiabetic patients.     

Dysregulated autophagy in the RPE is associated with increased susceptibility to oxidative stress and AMD

Autophagic dysregulation has been suggested in a broad range of neurodegenerative diseases including age-related macular degeneration (AMD). To test whether the autophagy pathway plays a critical role to protect retinal pigmented epithelial (RPE) cells against oxidative stress, we exposed ARPE-19 and primary cultured human RPE cells to both acute (3 and 24 h) and chronic (14 d) oxidative stress and monitored autophagy by western blot, PCR, and autophagosome counts in the presence or absence of autophagy modulators. Acute oxidative stress led to a marked increase in autophagy in the RPE, whereas autophagy was reduced under chronic oxidative stress. Upregulation of autophagy by rapamycin decreased oxidative stress-induced generation of reactive oxygen species (ROS), whereas inhibition of autophagy by 3-methyladenine (3-MA) or by knockdown of ATG7 or BECN1 increased ROS generation, exacerbated oxidative stress-induced reduction of mitochondrial activity, reduced cell viability, and increased lipofuscin. Examination of control human donor specimens and mice demonstrated an age-related increase in autophagosome numbers and expression of autophagy proteins. However, autophagy proteins, autophagosomes, and autophagy flux were significantly reduced in tissue from human donor AMD eyes and 2 animal models of AMD. In conclusion, our data confirm that autophagy plays an important role in protection of the RPE against oxidative stress and lipofuscin accumulation and that impairment of autophagy is likely to exacerbate oxidative stress and contribute to the pathogenesis of AMD.     

Dysregulated autophagy in the RPE is associated with increased susceptibility to oxidative stress and AMD

Autophagic dysregulation has been suggested in a broad range of neurodegenerative diseases including age-related macular degeneration (AMD). To test whether the autophagy pathway plays a critical role to protect retinal pigmented epithelial (RPE) cells against oxidative stress, we exposed ARPE-19 and primary cultured human RPE cells to both acute (3 and 24 h) and chronic (14 d) oxidative stress and monitored autophagy by western blot, PCR, and autophagosome counts in the presence or absence of autophagy modulators. Acute oxidative stress led to a marked increase in autophagy in the RPE, whereas autophagy was reduced under chronic oxidative stress. Upregulation of autophagy by rapamycin decreased oxidative stress-induced generation of reactive oxygen species (ROS), whereas inhibition of autophagy by 3-methyladenine (3-MA) or by knockdown of ATG7 or BECN1 increased ROS generation, exacerbated oxidative stress-induced reduction of mitochondrial activity, reduced cell viability, and increased lipofuscin. Examination of control human donor specimens and mice demonstrated an age-related increase in autophagosome numbers and expression of autophagy proteins. However, autophagy proteins, autophagosomes, and autophagy flux were significantly reduced in tissue from human donor AMD eyes and 2 animal models of AMD. In conclusion, our data confirm that autophagy plays an important role in protection of the RPE against oxidative stress and lipofuscin accumulation and that impairment of autophagy is likely to exacerbate oxidative stress and contribute to the pathogenesis of AMD.     

Reactive carbonyls and polyunsaturated fatty acids produce a hydroxyl radical-like species: a potential pathway for oxidative damage of retinal proteins in diabetes

The pattern of oxidized amino acids in aortic proteins of nonhuman primates suggests that a species resembling hydroxyl radical damages proteins when blood glucose levels are high. However, recent studies argue strongly against a generalized increase in diabetic oxidative stress, which might instead be confined to the vascular wall. Here, we describe a pathway for glucose-stimulated protein oxidation and provide evidence of its complicity in diabetic microvascular disease. Low density lipoprotein incubated with pathophysiological concentrations of glucose became selectively enriched in ortho-tyrosine and meta-tyrosine, implicating a hydroxyl radical-like species in protein damage. Model system studies demonstrated that the reaction pathway requires both a reactive carbonyl group and a polyunsaturated fatty acid, involves lipid peroxidation, and is blocked by the carbonyl scavenger aminoguanidine. To explore the physiological relevance of the pathway, we used mass spectrometry and high pressure liquid chromatography to quantify oxidation products in control and hyperglycemic rats. Hyperglycemia raised levels of ortho-tyrosine, meta-tyrosine, and oxygenated lipids in the retina, a tissue rich in polyunsaturated fatty acids. Rats that received aminoguanidine did not show this increase in protein and lipid oxidation. In contrast, rats with diet-induced hyperlipidemia in the absence of hyperglycemia failed to exhibit increased protein and lipid oxidation products in the retina. Our observations suggest that generation of a hydroxyl radical-like species by a carbonyl/polyunsaturated fatty acid pathway might promote localized oxidative stress in tissues vulnerable to diabetic damage. This raises the possibility that antioxidant therapies that specifically inhibit the pathway might delay the vascular complications of diabetes.     

TBARS的新应用--表征羰基紧张

以硫代巴比妥酸(TBA)方法测得的所谓丙二醛(MDA)水平已被广泛用作诊断组织伤害和脂过氧化程度的指标。但TBA方法对MDA的特异性很有争议,MDA只是氧化伤害和脂质过氧化产生的诸多不饱和醛酮产物中主要产物的一种。由于硫代巴比妥酸反应产物(TBARS)涵盖了大部分氧化伤害产生的醛酮类物质,因而TBARS可被用作为衡量羰基紧张的很好的指标。     

Glycation <Emphasis Type="Italic">vs</Emphasis>. glycosylation: a tale of two different chemistries and biology in Alzheimer’s disease

In our previous studies, we reported that the activity of an anti-oxidant enzyme, Cu,Zn-superoxide dismutase (Cu,Zn-SOD) became decreased as the result of glycation in vitro and in vivo. Glycated Cu,Zn-SOD produces hydroxyl radicals in the presence of transition metals due to the formation of a Schiff base adduct and a subsequent Amadori product. This results in the site-specific cleavage of the molecule, followed by random fragmentation. The glycation of other anti-oxidant enzymes such as glutathione peroxidase and thioredoxin reductase results in a loss or decrease in enzyme activity under pathological conditions, resulting in oxidative stress. The inactivation of anti-oxidant enzymes induces oxidative stress in aging, diabetes and neurodegenerative disorders. It is well known that the levels of Amadori products and N^e-(carboxylmethyl)lysine (CML) and other carbonyl compounds are increased in diabetes, a situation that will be discussed by the other authors in this special issue. We and others, reported that the glycation products accumulate in the brains of patients with Alzheimer’s disease (AD) patients as well as in cerebrospinal fluid (CSF), suggesting that glycation plays a pivotal role in the development of AD. We also showed that enzymatic glycosylation is implicated in the pathogenesis of AD and that oxidative stress is also important in this process. Specific types of glycosylation reactions were found to be up- or downregulated in AD patients, and key AD-related molecules including the amyloid-precursor protein (APP), tau, and APP-cleaving enzymes were shown to be functionally modified as the result of glycosylation. These results suggest that glycation as well as glycosylation are involved in oxidative stress that is associated with aging, diabetes and neurodegenerative diseases such as AD.     

Assessment of protein oxidation in women using raloxifene

Objectives. To assess the oxidative effects of raloxifene use in postmenopausal women by investigating protein carbonyl levels in the plasma. Methods. Nineteen osteoporotic postmenopausal women treated with raloxifene for 12 months were included in the study. Another seventeen postmenopausal women matched for age and postmenopausal years, without any medication were chosen as a control group. Protein carbonyl levels were determinated as oxidative stress markers by the use of Levine's method in the plasma of these women. Results. Serum protein carbonyl levels of postmenopausal women treated with raloxifene (1.27 ± 0.32 nmol/mg protein) were significantly lower than the control group (2.18 ± 0.27 nmol/mg protein) (p < 0.05). Conclusions. Oxidative stress has been found responsible for several diseases including cancer. Protein carbonyl levels, which are the products of protein oxidation, are one of the indicatives of oxidative stress. Therefore, the decline in protein carbonyl levels in this study revealed the decreasing oxidative stress. According to our results, it might be interpreted that raloxifene does not cause oxidative stress, and it may even have protective effects in long-term use.