阿片样物质与心脏缺血预处理

阿片肽和外源性阿片术物质如吗啡除了能缓解心肌梗塞造成的疼痛外,还具有减小梗塞范围和降低心律失常的发生等重要作用。心脏阿片受体参与了缺血预处理（IPC）对心脏的调节作用,阿片样物质激活心脏阿片受体还可模拟IPC对心脏的作用。心脏阿片受体的激活产生的急性即第一窗口期和延迟即第二窗口期的心脏保护作用的信号途径,与IPC相似,其信号通路涉及Gi/Go蛋白、蛋白激酶C、酪氨酸激酶和ATP敏感K^ 通道等途径。     

Kappa 阿片受体的抗缺血性心脏保护作用--信息机制

有证据表明,心脏细胞产生强腓肽和强腓肽类多肽,它们是kappa阿片受体(κ-0R)的激动剂。κ-0R是心脏一种优势的阿片受体,其激活可改变在体和离体心脏的功能。在正常和病理情况下,内源性κ-阿片肽可能通过自分泌或旁分泌的方式调节心脏功能。心肌缺血是导致心脏功能紊乱的一个常见原因,主要表现为心肌功能减弱,心律失常及心肌梗塞等。心肌缺血时,交感神经发放增强,从而增加作功负荷及氧消耗量;而这又使缺血引发的状况更为恶化。机体抵抗缺血引发心肌损害／心律失常的保护机制之一是抑制β-肾上腺素受体(β—AR)的兴奋。κ-0R确实能抑制β-AR的激动。这种抑制主要是由于GS蛋白受到抑制,也在较小程度上由于信息通路的腺苷酸环化酶的抑制。因为该种酶能通过对百日咳毒素敏感的G蛋白转导β—AR的激动。另一保护心肌对抗缺血性损害的机制是预处理。预处理是指预先受到缺血等损伤使心脏对随后更严重的损伤产生较强的耐受能力。这种保护作用可以在预处理后即时产生,也可延至预处理后1—3天。在采用缺血或其产生的后果之一——代谢抑制作为预处理而致的心脏保护中,κ-OR参与媒介预处理的作用。用κ—OR的特异性激动剂U50488H激活κ—OR(U50488H药理性预处理,UP)可激活蛋白激酶C(PKC),开放ATY敏感的钾通道(KATP channels)及增加热休克蛋白(HSP)的产生。阻断PKC的作用,关闭KATP通道或抑制HSP的合成,均可消除UP的心脏保护作用。这些发现表明,PKC、KATP通道和HSP在UP的心脏保护中均具重要作用。此外,UP也能减低缺血造成心肌损害的因素之一,即Ca^2 的超负荷。这个事实表明UP发挥心脏保护作用至少部分地是通过减低Ca^2 的超负荷。最有趣的是,以阻断剂阻塞KATP通道,在消除UP的延迟性心脏保护作用的同时也降低了UP对Ca^2 超负荷的抑制作用。这个事实揭示了KATP通道开放所致的心脏保护作用至少部分地可能是由于防止或减低了Ca^2 的超负荷。     

缺血后处理内源性心脏保护的研究进展

再灌注疗法是临床治疗心肌缺血最有效的措施,但会引起再灌注损伤,调动机体内源性保护机制可以减轻再灌注损伤,保护缺血心肌。缺血预处理（ischemic preconditioning,IPC）和后处理（ischemic postconditioning,I-postC）是缺血心脏有效的内源性保护现象,可以减轻缺血再灌注（ischemia／reperfusion,I／R）后心肌坏死与心肌功能障碍,减少恶性心律失常的发生。内源性心脏保护的机制主要是通过诱导触发因子释放,经多条细胞内信号转导途径的介导,作用于多种效应器,影响氧自由基产生、钙超载等I／R损伤的关键环节而发挥心肌细胞保护作用。特别是可以在缺血后实施的I-postC具有良好的临床应用前景。本文以I-postC为重点综述内源性心脏保护作用、机制及其临床应用现状。     

迷走神经和乙酰胆碱对缺血心肌保护作用的研究新进展

缺血性心脏病是危害人类健康的主要疾病之一。新近研究发现,心肌缺血与迷走神经活性降低及交感神经活性升高密切相关。本文从缺血性心脏病时心脏迷走神经调控的改变、迷走神经及其递质乙酰胆碱对缺血心肌的保护作用和其在缺血预适应、缺血后适应中可能的信号转导途径等方面,对迷走神经及其递质保护缺血心肌的作用机制研究的新进展予以综述,将有助于深入理解缺血性心脏病的发病机制及防治措施,为该疾病的防治开辟新思路。     

内源性阿片物质参与大鼠缺血预处理的心肌保护作用

实验以离体灌流的ＳＤ大鼠心脏为模型,用ｋ特异性拮抗剂的ＭＲ２２６６研究ｋ阿片受体的阻断与缺血预处理的关系,用放射免疫分析法研究ＩＰ及长时间缺血对心肌强啡肽Ａ１－１３浓度的影响,探索Ｋ阿片物质在ＩＰ过程中的作用和地位。     

骨骼肌缺血预适应对猪心肌凋亡的影响及阿片受体的作用

目的:确定骨骼肌缺血预适应对猪心肌凋亡及其调控基因Bcl-2/Bax的影响,并探讨阿片受体在此机制中可能的作用。方法:采用非开胸法建立猪心脏缺血/再灌注(I/R)模型,通过球囊堵塞左股动脉造成骨骼肌短暂缺血,分别使用阿片受体拮抗剂纳洛酮以及神经节阻断剂六烃己胺进行干预。采用末端探针标记及流式细胞技术检测心肌凋亡细胞及调控基因Bcl-2/Bax,确定各组对以上指标的影响。结果:①和缺血对照组(CONT组)相比,远端预处理后心肌细胞凋亡率明显降低(4.43%±0.74%vs15.4%±1.15%,P<0.05),提示骨骼肌远端预适应(RP)可减少心肌凋亡。②和CONT组相比,远端预处理后Bcl-2/Bax比值明显增高(1.36±0.09vs0.56±0.08,P<0.05),提示RP对心肌凋亡的影响可能通过影响Bcl-2/Bax进行调控。③预处理前使用阿片受体拮抗剂纳洛酮可使以上保护作用减弱(P<0.05),但纳洛酮对CONT组无影响。④预处理前使用神经节阻断剂六烃己胺,不影响RP对心肌的保护作用。结论:骨骼肌缺血预适应减少心肌细胞凋亡,可能通过影响Bcl-2/Bax进行调控;阿片受体可能参与此保护作用,且不通过神经反射进行。     

黄鼠与大鼠离体心脏预缺血处理对缺血再灌损伤的保护作用

本文用黄鼠和大鼠离体心脏比较了两种预缺血处理方案对随后缺血再灌损伤的作用。用Ｌａｎｇｅｎｄｏｒｆｆ方法灌流秋季未入眠的达乌尔黄鼠和Ｗｉｓｔａｒ大鼠离体心脏,以冠脉流出液中肌酸激酶（ＣＫ）释放活性、心律失常发生率、心功能恢复等为指标,检验不同预缺血处理时间对随后缺血再灌损伤的影响。标本平衡１０ｍｉｎ后对照组的两种动物经受缺灌１５ｍｉｎ再灌１５ｍｉｎ预缺血处理,接着进行两次缺灌１０ｍｉｎ再灌１０ｍｉｎ     

脑预缺血引起大鼠海马细胞膜腺苷受体数量和亲和力升高及其对神经元的保护作用

采用放射性配基结合法,测定大鼠全脑缺血后海马细胞膜腺苷(adenosine,ADO)受体数量及亲和力的变化,以探讨其与脑缺血耐受形成之间的关系。发现缺血6min即可导致海马组织明显的神经元延迟性死亡(delayed neuron     

无创性肢体缺血预适应对小鼠抗应激能力的影响

目的:探讨无创性肢体缺血预适应在提高小鼠抗应激能力方面的作用。方法:小鼠分为正常组、对照组、预适应组和药物组,进行常压耐缺氧、耐疲劳负重游泳、耐高、低温实验,分别记录各种应激状态下小鼠的耐受时间,测定常压缺氧耐受后小鼠血清中SOD的活性和负重游泳后血清中乳酸的含量。结果:预适应组能显著提高小鼠常压耐缺氧时间,且SOD活性较对照组有显著的提高,但提高的程度均低于普萘洛尔组。预适应组平均游泳时间显著延长,且程度与咖啡因组相当。预适应能明显延长高温下小鼠的存活时间,且延长程度与氯丙嗪没有显著性差异。与正常组比较,预适应组能显著延长小鼠的耐低温时间。结论:无创性肢体缺血预适应能提高小鼠耐缺氧、抗疲劳、耐高温和耐低温的能力。     

δ-阿片受体在缺血后处理心肌保护中的作用

目的：探讨δ-阿片受体是否参与缺血后处理对抗心肌缺血/复灌（I/R）损伤和心肌细胞低氧/复氧（H/R）损伤作用及其机制。方法：采用离体大鼠心脏Langendorff灌流模型,全心停灌30 min、复灌120 min复制I/R模型。测定心室力学指标和复灌时冠脉流出液中乳酸脱氢酶（lactate dehydrogenase,LDH）活性,实验结束测定心肌组织formazan含量。酶解分离的心肌细胞采用低氧60min、复氧60min复制H/R模型,测定心肌细胞存活率。结果：在离体心脏模型上,与I/R组相比,缺血后处理组（停灌后复灌即刻立即给予6次全心停灌/复灌循环）心肌组织的formazan含量明显增高,复灌期间冠脉流出液中LDH明显降低,同时缺血后处理明显改善心室力学指标,缓解冠脉流量的减少 在分离心肌细胞模型上,低氧后处理明显提高心肌细胞存活率。δ-阿片受体阻断剂naltrindole（NTI）和线粒体钙激活钾通道（KCa）阻断剂paxilline（Pax）在离体大鼠心脏模型和分离心肌细胞模型上均能明显减弱缺血后处理的作用。在心肌细胞模型上,与H/R组相比,δ-阿片受体激动剂DADLE明显提高心肌细胞存活率,其作用可被paxilline所阻断。结论：缺血后处理具有抗心肌缺血/复灌损伤的作用,这种保护作用可能与其激活δ-阿片受体和开放KCa有关。     

Anti-RANKL therapy for inflammatory bone disorders: Mechanisms and potential clinical applications

Focal bone loss around inflamed joints in patients with autoimmune disease, such as rheumatoid arthritis, remains a serious clinical problem. The recent elucidation of the RANK/RANK-ligand/OPG pathway and its role as the final effector of osteoclastogenesis and bone resorption has brought a tremendous understanding of the pathophysiology of inflammatory bone loss, and has heightened expectation of a novel intervention. Here, we review the etiology of inflammatory bone loss, the RANK/RANK-ligand/OPG pathway, and the clinical development of anti-RANK-ligand therapy.     

Mechanisms underlying the cardioprotective effects of omega-3 polyunsaturated fatty acids

Typical omega 3 polyunsaturated fatty acids (n-3 PUFAs) are docosahexaenoic acid and eicosapentaenoic acid in the form of fish oils and α linolenic acid from flaxseed oil. Epidemiological studies suggested the benefits of n-3 PUFA on cardiovascular health. Intervention studies confirmed that the consumption of n-3 PUFA provided benefits for primary and secondary prevention of cardiovascular disease. Evidence from cellular and molecular research studies indicates that the cardioprotective effects of n-3 PUFA result from a synergism between multiple, intricate mechanisms that involve antiinflammation, proresolving lipid mediators, modulation of cardiac ion channels, reduction of triglycerides, influence on membrane microdomains and downstream cell signaling pathways and antithrombotic and antiarrhythmic effects. n-3 PUFAs inhibit inflammatory signaling pathways (nuclear factor-κ B activity) and down-regulate fatty acid (FA) synthesis gene expression (sterol regulatory element binding protein-1c) and up-regulate gene expression involved in FA oxidation (peroxisome proliferator-activated receptor α). This review examines the various mechanisms by which n-3 PUFA exert beneficial effects against CVD.     

Mechanisms of action of neuropeptide Y on stem cells and its potential applications in orthopaedic disorders

Musculoskeletal disorders are the leading causes of disability and result in reduced quality of life. The neuro-osteogenic network is one of the most promising fields in orthopaedic research. Neuropeptide Y (NPY) system has been reported to be involved in the regulations of bone metabolism and homeostasis, which also provide feedback to the central NPY system via NPY receptors. Currently, potential roles of peripheral NPY in bone metabolism remain unclear. Growing evidence suggests that NPY can regulate biological actions of bone marrow mesenchymal stem cells, hematopoietic stem cells, endothelial cells, and chondrocytes via a local autocrine or paracrine manner by different NPY receptors. The regulative activities of NPY may be achieved through the plasticity of NPY receptors, and interactions among the targeted cells as well. In general, NPY can influence proliferation, apoptosis, differentiation, migration, mobilization, and cytokine secretion of different types of cells, and play crucial roles in the development of bone delayed/non-union, osteoporosis, and osteoarthritis. Further basic research should clarify detailed mechanisms of action of NPY on stem cells, and clinical investigations are also necessary to comprehensively evaluate potential applications of NPY and its receptor-targeted drugs in management of musculoskeletal disorders.     

The cardioprotective potential of hydrogen sulfide in myocardial ischemia/reperfusion injury (review)

Myocardial infarction is responsible for the majority of cardiovascular mortality and the pathogenesis of myocardial damage during and after the infarction involves reactive oxygen species. Serious efforts are under way to modulate the developing ischemia/reperfusion injury and recently the use of hydrogen sulfide (H2S) emerged as a new possibility. H2S has been best known for decades as a pungent toxic gas in contaminated environmental atmosphere, but it has now been recognized as a novel gasotransmitter in the central nervous and cardiovascular systems, similarly to nitric oxide (NO) and carbon monoxide (CO). This finding prompted the investigation of the potential of H2S as a cardioprotective agent and various in vitro and in vivo results demonstrate that H2S may be of value in cytoprotection during the evolution of myocardial infarction. Although several questions remain to be elucidated about the properties of this new gasotransmitter, increased H2S levels may have therapeutic potential in clinical settings in which ischemia/reperfusion injury is encountered. This review article overviews the current understanding of the effects of this exciting molecule in the setting of myocardial ischemia/reperfusion.     

Nanobiocatalysis and its potential applications

Nanobiocatalysis, in which enzymes are incorporated into nanostructured materials, has emerged as a rapidly growing area. Nanostructures, including nanoporous media, nanofibers, carbon nanotubes and nanoparticles, have manifested great efficiency in the manipulation of the nanoscale environment of the enzyme and thus promise exciting advances in many areas of enzyme technology. This review will describe these recent developments in nanobiocatalysis and their potential applications in various fields, such as trypsin digestion in proteomic analysis, antifouling, and biofuel cells.     

COX-2-dependent and potentially cardioprotective effects of negative inotropic substances released after ischemia

During reperfusion, cardiodepressive factors are released from isolated rat hearts after ischemia. The present study analyzes the mechanisms by which these substances mediate their cardiodepressive effect. After 10 min of global stop-flow ischemia, rat hearts were reperfused and coronary effluent was collected over a period of 30 s. We tested the effect of this postischemic effluent on systolic cell shortening and Ca(2+) metabolism by application of fluorescence microscopy of field-stimulated rat cardiomyocytes stained with fura-2 AM. Cells were preincubated with various inhibitors, e.g., the cyclooxygenase (COX) inhibitor indomethacin, the COX-2 inhibitors NS-398 and lumiracoxib, the COX-1 inhibitor SC-560, and the potassium (ATP) channel blocker glibenclamide. Lysates of cardiomyocytes and extracts from whole rat hearts were tested for expression of COX-2 with Western blot analysis. As a result, in contrast to nonischemic effluent (control), postischemic effluent induced a reduction of Ca(2+) transient and systolic cell shortening in the rat cardiomyocytes (P < 0.001 vs. control). After preincubation of cells with indomethacin, NS-398, and lumiracoxib, the negative inotropic effect was attenuated. SC-560 did not influence the effect of postischemic effluent. The inducibly expressed COX-2 was detected in cardiomyocytes prepared for fluorescence microscopy. The effect of postischemic effluent was eliminated with applications of glibenclamide. Furthermore, postischemic effluent significantly reduced the intracellular diastolic and systolic Ca(2+) increase (P < 0.01 vs. control). In conclusion, the cardiodepressive effect of postischemic effluent is COX-2 dependent and protective against Ca(2+) overload in the cells.     

Comparative study of the cardioprotective effects of local and remote preconditioning in ischemia/reperfusion injury

AimsThough the cardioprotective effects of local or remote preconditioning have been estimated, it is still unclear which of them is more reliable and provides more cardioprotection. The present investigation was directed to compare, in one study, the cardioprotective effects of different cycles of local or remote preconditioning in ischemia/reperfusion (I/R)-induced electrophysiological, biochemical and histological changes in rats.Main methodsRats were randomly assigned into 10 groups. Groups 1 and 2 were normal and I/R groups, respectively. Other groups were subjected to 1, 2, 3, 4 cycles of local or remote preconditioning before myocardial I/R (40 min/10 min). Heart rate and ventricular arrhythmias were recorded during I/R progress. At the end of reperfusion, plasma creatine kinase-MB (CK-MB) activity and total nitrate/nitrite (NO_x) were determined. In addition, lactate, adenine nucleotides, thiobarbituric acid reactive substances (TBARS), reduced glutathione (GSH) and myeloperoxidase (MPO) activity were estimated in the heart left ventricle. Histological examination was also performed to visualize the protective cellular effects of the effective cycle of local or remote preconditioning.Key findingsIn general, local preconditioning was more effective than remote preconditioning in reducing ventricular arrhythmias, CK-MB release, lactate accumulation and elevated MPO activity as well as preserving adenine nucleotides. Concerning the most effective group in each therapy, 3 cycles of local preconditioning provided more cardioprotection than that of remote preconditioning in the histological examination.SignificanceDespite being invasive, local preconditioning provided more effective cardioprotection than remote preconditioning in ameliorating the overall electrophysiological, biochemical and histological changes.     

Role of heme oxygenase-1 in the cardioprotective effects of erythropoietin during myocardial ischemia and reperfusion

We have recently demonstrated that erythropoietin (EPO) protects cardiomyocytes from apoptosis during myocardial ischemia-reperfusion (I/R). The objective of the present study was to investigate the role of heme oxygenase (HO)-1 in the antiapoptotic effects of EPO. Primary cultures of neonatal mouse cardiomyocytes were subjected to anoxia-reoxygenation (A/R). Pretreatment with EPO significantly reduced apoptosis in A/R-treated cells. This reduction in apoptosis was preceded by an increase in the mRNA and protein expression of HO-1. Selective inhibition of HO-1 using chromium mesoporphyrin (CrMP) significantly diminished the ability of EPO to inhibit apoptosis. Cotreatment of EPO with SB-202190, an inhibitor of p38 activation, blocked the EPO-mediated HO-1 expression and antiapoptotic effects, suggesting a p38-dependent mechanism. The in vivo significance of p38 and HO-1 as mediators of EPO's cardioprotection was investigated in mice subjected to myocardial I/R. Pretreatment with EPO decreased infarct size as well as I/R-induced apoptosis in wild-type mice. However, these effects were significantly diminished in HO-1(-/-) mice. Furthermore, EPO given during ischemia reduced infarct size in mice subjected to I/R, and this effect was blocked by CrMP treatment in wild-type mice. Moreover, inhibition of p38 diminished the cardioprotective effects of EPO. We conclude that upregulation of HO-1 expression via p38 signaling contributes to EPO-mediated cardioprotection during myocardial I/R.     

Mechanisms underlying the cardioprotective effect of l-cysteine

In many tissues the availability of l-cysteine is a rate-limiting factor in glutathione production, though this has yet to be fully tested in heart. This study aimed to test the hypothesis that supplying hearts with 0.5 mM l-cysteine would preserve glutathione levels leading to an increased resistance to ischaemia reperfusion.Left ventricular function was measured in isolated perfused rat hearts before, during and after exposure to 45 min global normothermic ischaemia. Control hearts received Krebs throughout, whilst in treated hearts 0.5 mM l-cysteine was added to the perfusate 10 min before ischaemia, and was then present throughout ischaemia and for the first 10 min of reperfusion. Reperfusion injury was assessed from the appearance of lactate dehydrogenase (LDH) in the effluent. In two separate groups of control and treated hearts, ATP and glutathione (GSH) contents were measured at the beginning and end of ischaemia.Hearts treated with 0.5 mM l-cysteine showed a significantly higher recovery of rate pressure product (16,256± 1288 mmHg bpm vs. 10,324± 2102 mmHg bpm, p < 0.05) and a significantly lower release of LDH (0.54± 0.16 IU/g wet weight vs. 1.44± 0.31 IU/g wet weight, p < 0.05) compared to controls. Also, the l-cysteine treated group showed significantly better preservation of ATP and GSH during ischaemia in comparison to control.These results suggest that the mechanisms underlying the cardioprotective effects of 0.5 mM l-cysteine may include: increased anaerobic energy production either directly or through reduced degradation of adenine nucleotides; direct scavenging of free radicals; and/or improved antioxidant capacity through glutathione preservation.     

Mechanisms,function and clinical applications of DNp73

p73, has two distinct promoters, which allow the formation of two protein isoforms: full-length transactivating (TA) p73 and an N-terminally truncated p73 species (referred to as DNp73) that lacks the N-terminal transactivating domain. Although the exact cellular function of DNp73 is unclear, the high expression levels of the genes have been observed in a variety of human cancers and cancer cell lines and have been connected to pro-tumor activities. Hence the aim of this review is to summarize DNp73 expression status in cancer in the current literature. Furthermore, we also focused on recent findings of DNp73 related to the biological functions from apoptosis, chemosensitivity, radiosensitibity, differentiation, development, etc. Thus this review highlights the significance of DNp73 as a marker for disease severity in patients and as target for cancer therapy.