抗氧化剂抑制缺血后再灌注损伤相关的心肌细胞凋亡

目的研究抗氧化剂对缺血后再灌注引起的心肌细胞凋亡的作用。方法利用缺血再灌注损伤的动物模型,通过末端转移酶介导的原位缺口标记法（ＴＵＮＥＬ）检测有或无药物保护时心肌细胞的凋亡程度。结果与非缺血心肌比较,缺血再灌注的心肌组织出现显著的凋亡细胞,而经抗氧化剂Ｎ－乙酰－Ｌ－半胱氨酸（ＮＡＣ）预处理的缺血再灌注大鼠心肌组织凋亡细胞数较未处理组显著减少。结论ＮＡＣ可有效抑制缺血再灌注损伤相关的心肌细胞凋亡。     

肿瘤坏死因子、缺血再灌注损伤和心肌细胞凋亡

肿瘤坏死因子在心脏疾病中的作用一直是研究热点。本文综述了肿瘤坏死因子在缺血再灌注损伤、心肌细胞凋亡方面的最新研究进展。     

缺血再灌注损伤与急性胰腺炎

急性胰腺炎(acute pancreatitis, AP)的发病机制尚不明确, 通过动物实验及临床研究发现, 缺血再灌注损伤在其发病机制中具有重要作用.微循环障碍、自由基生成增多、细胞内钙超载, 炎性介质、白细胞及血小板的作用、肠源性内毒素血症等因素综合作用导致胰腺缺血再灌注损伤, 这可能是AP发病环节中的共同通路. 本文就胰腺缺血再灌注损伤的发生机制作一综述.     

MG-132抑制大鼠缺血再灌注心肌细胞凋亡

目的观察蛋白酶体抑制剂MG-132对急性缺血再灌注大鼠心肌细胞凋亡的影响。方法建立大鼠心肌缺血再灌注模型,治疗组及治疗对照组于再灌注前5min静脉注射MG-132(0.75mg/kg),缺血再灌注组及假手术组注射生理盐水,观察各组心肌组织炎症细胞浸润及心肌细胞凋亡情况。结果MG-132能显著抑制心肌梗死周围组织嗜中性粒细胞的浸润;与缺血再灌注组相比,治疗组核因子κBmRNA水平和蛋白水平显著降低(P<0.05);治疗组再灌注2h、6h及24h亚组凋亡指数较缺血再灌注组同时间点显著下降;与缺血再灌注组相比,Bax的积分光密度值降低(P<0.05),Bcl-2蛋白水平明显上调,Bcl-2/Bax比值显著增加。结论蛋白酶体抑制剂能够抑制急性缺血再灌注心肌的凋亡,具有心肌保护作用。     

粉防己碱抑制心肌细胞磷酸化减轻缺血/再灌注损伤引发的炎症反应

目的:探讨心肌缺血/再灌注过程中粉防己碱(Tet)对核转录因子(NF)-κB的抑制因子(IκB-α)磷酸化及肿瘤坏死因子-α(TNF-α)、白细胞介素-6(IL-6)表达的影响以及机制。方法:60只SD大鼠被随机分为3组:缺血/再灌注损伤组(I/R)、假手术组、粉防己碱治疗组(Tet)。I/R组结扎大鼠左前降支造成心肌缺血30min后再灌注24h,然后处死大鼠;假手术组只穿针不结扎,余步骤同I/R组;Tet组在缺血前20min腹腔注射Tet,余步骤同I/R组。处死大鼠24h后取心肌标本,用酶联免疫吸附法(ELISA)检测心肌组织中TNF-α、IL-6表达水平,应用免疫组织化学方法检测磷酸化IκB-α(P-IκB-α)的表达。结果:Tet组与I/R组相比TNF-α、IL-6表达水平明显减低[(208.40±25.12)pg/ml∶(306.65±17.78)pg/ml,(587.40±137.40)pg/ml∶(1003.75±138.33)pg/ml,P均0.01],而Tet组与假手术组相比表达明显增强[(208.40±25.12)pg/ml∶(61.45±9.20)pg/ml,(587.40±137.40)pg/ml∶(229.25±90.13)pg/ml,P均0.01]。Tet组大鼠心肌细胞胞浆中P-IκB-α的表达明显低于I/R组[(0.0817±0.09)pg/ml∶(0.1755±0.01)pg/ml,但明显高于假手术组[(0.0817±0.09)pg/ml∶(0.0513±0.03)pg/ml,P均0.01]。结论:Tet可以抑制IκB-α磷酸化,显著减少前炎症因子TNF-α、IL-6的产生,减轻心肌缺血/再灌注损伤。     

心肌细胞凋亡在老年性缺血再灌注后心力衰竭发生中的作用

目的探讨年龄对急性心肌梗死(AMI)患者心肌细胞凋亡以及心功能的影响。方法选择2010年10月～2012年12月在我院心内科住院的急性心肌梗死(AMI)患者65例,分为年龄<65岁组(AMI 1组)29例,年龄≥65岁组(AMI 2组)36例。另选健康志愿者45例,分为年龄<65岁组(志愿1组)24例,年龄≥65岁组(志愿2组)21例。AMI 1组和AMI 2组患者均在发病6h内接受急诊PCI,并于术后1、3和5d检测可溶性脂肪合成酶(sFas)、白细胞介素(IL)6、TNF-α和心肌肌钙蛋白I(cTnI)水平。在入院即刻及第5天进行超声多普勒检查并采用Killip分级评价心功能。结果与志愿1组、AMI 1组比较,志愿2组、AMI 2组LVEF、左心室缩短分数(LVFS)、二尖瓣舒张早期血流峰值(E)/二尖瓣舒张晚期血流峰值(A)比值明显降低(P<0.01);与AMI 1组比较,AMI 2组Killip分级、sFas、IL-6、TNF-α及PCI术后1、3和5dcTnI水平均明显升高(P<0.01)。结论老龄化加剧了心肌缺血再灌注后心肌的损伤,心肌细胞凋亡水平的差异在其中可能起到了关键的作用。     

肿瘤坏死因子-α基因表达、细胞凋亡与急性胰腺炎肺损伤关系的实验研究

目的 观察急性胰腺炎时肺内肿瘤坏死因子-α（TNF-α）基因表达及细胞凋亡的状况，并探讨其与肺损伤的关系。方法 以不同浓度牛磺胆酸钠液逆行胰胆管注射造成大鼠急性水肿性胰腺炎（AEP）与急性坏死性胰腺炎（ANP）两种模型，测定血浆TNF－α水平；半定量RT－PCR及免疫组化检测肺组织内TNF－α基因表达水平；TUNEL法结合激光扫描共聚焦显微镜检测肺内细胞凋亡的情况。结果 诱导AEP后肺内TNF－αmRNA及其蛋白的表达呈短暂的一过性增强，这种表达在ANP组则更为强烈与持久，与ANP组发生明显肺损伤相关（P＜0．05）。肺内细胞凋亡指数（‰）在AEP组呈一过性下降，在ANP组呈持续下降，其变化与肺损伤程度及肺内TNF－α mRNA水平呈负相关（P＜0．05）。结论 ANP时肺内TNF－α基因转录表达过度上调，代表一种超强的全身炎症反应即全身炎症反应综合征（SIRS),民肺损伤的发生有关。同时，肺内浸润的炎细胞（主要是中性粒细胞）发生延迟凋亡，可能在肺损伤进程中起作用，而TNF－α的过度生成是中性粒细胞延迟凋亡的部分原因。     

心肌细胞凋亡与缺血/再灌注损伤

细胞凋亡（apoptosis）是细胞死亡的一种重要形式，即程序性细胞死亡，一般认为它是由基因控制的、有序化的主动死亡过程。自1972年Kerr等首次以形态学概念提出细胞凋亡这一术语以来，凋亡一直是医学界的研究热点。近年来，随着分子生物学技术的不断丰富及分子心血管病学的研究发展，已证实细胞凋亡现象存在于心血管系统的许多生理和病理变化中，与许多心血管疾病的发生发展密切相关。本文就心肌细胞凋亡与缺血再灌注损伤的关系综述如下。     

肺移植后缺血再灌注损伤发病机制的研究进展

本文综述了肺移植后缺血再灌注损伤(IRI)发病机制的研究进展,包括:①白细胞活化;②转录因子激活;③细胞膜分子的上调;④促炎症反应介质的释放;⑤蛋白酶的释放;⑥IRI的保护性物质。肺移植IRI中表现为多基因改变导致的疾病,对肺移植IRI进行基因治疗的策略,靶标应选择具有调控其它致病基因功能的关键基因。     

Status of myocardial antioxidants in ischemia-reperfusion injury

BACKGROUND: Myocardial ischemia-reperfusion represents a clinically relevant problem associated with thrombolysis, angioplasty and coronary bypass surgery. Injury of myocardium due to ischemia-reperfusion includes cardiac contractile dysfunction, arrhythmias as well as irreversible myocyte damage. These changes are considered to be the consequence of imbalance between the formation of oxidants and the availability of endogenous antioxidants in the heart. OBSERVATIONS: An increase in the formation of reactive oxygen species during ischemia-reperfusion and the adverse effects of oxyradicals on myocardium have now been well established by both direct and indirect measurements. Although several experimental studies as well as clinical trials have demonstrated the cardioprotective effects of antioxidants, some studies have failed to substantiate the results. Nonetheless, it is becoming evident that some of the endogenous antioxidants such as glutathione peroxidase, superoxide dismutase, and catalase act as a primary defense mechanism whereas the others including vitamin E may play a secondary role for attenuating the ischemia-reperfusion injury. The importance of various endogenous antioxidants in suppressing oxidative stress is evident from the depression in their activities and the inhibition of cardiac alterations which they produce during ischemia-reperfusion injury. The effects of an antioxidant thiol containing compound, N-acetylcysteine, and ischemic preconditioning were shown to be similar in preventing changes in the ischemic-reperfused hearts. CONCLUSIONS: The available evidence support the role of oxidative stress in ischemia-reperfusion injury and emphasize the importance of antioxidant mechanisms in cardioprotection.     

心肌缺血-再灌注损伤钙超载及其防治策略

缺血-再灌注(I-R)可引起肌膜损伤、Na+/Ca2+交换逆转以及肌(内)质网钙泵(SERCA)含量或活性下降从而导致心肌钙超载.钙超载诱导心肌Calpain活化与线粒体膜通透性转换孔(mPTP)开放进而引起心肌细胞收缩功能障碍、凋亡甚至坏死.通过抑制Na+/Ca2+交换蛋白、Na+/H+交换蛋白、Calpain活性、...     

Microvascular changes in liver after ischemia-reperfusion injury

Morphological changes in the hepatic microvasculature were studied in experimentally induced ischemia-reperfusion injury in the rat using a vascular casting technique. Partial hepatic ischemia was induced for 90 min followed by 24 hr of reperfusion. Microvascular casting was performed after 24 hr reperfusion by either intraarterial or intravenous infusion of acrylic resin (Mercox). After corrosion of the tissue, the cast was examined by scanning electron microscopy. Casts of normal livers showed good patency with no evidence of unfilled areas. The mean diameter of sinusoids was 14±3 µm with those in zone 1 slightly smaller than those in zone 3. Liver casts from rats subjected to ischemia and reperfusion resulted in gross disruption of normal architecture. The common characteristics seen in both prograde and retrograde casts were clusters of closed sinusoids around zones 2 and 3 of the liver acini, which resulted in cavities of various sizes. Varicosities were observed in some areas. The mean diameter of sinusoids in areas of patent microvascular structure (10±2 µm) was significantly smaller compared to those in normal livers (P<0.001). Misoprostol given at 1 min before reperfusion markedly reduced the microvascular injury. The hepatic microvasculature was generally intact with mild focal unfilled areas. The majority of the sinusoids were of normal size and no clusters of blind ending sinusoids were detected. The present study shows that hepatic ischemia-reperfusion results in extensive microvascular injury in the liver. The protective effects of misoprostol against this injury may occur at the vascular level.This study is supported by the Australian National Health and Medical Research Council Grant No. 91/0662 and Alfred Hospital, Victoria, Australia.     

Rapamycin confers preconditioning-like protection against ischemia-reperfusion injury in isolated mouse heart and cardiomyocytes

Rapamycin (sirolimus) is an antibiotic that inhibits protein synthesis through mammalian target of rapamycin (mTOR) signaling and is used as an immunosuppressant in the treatment of organ rejection in transplant recipients. Recently, the antigrowth properties of rapamycin have been utilized for cardiovascular benefit as stents impregnated with rapamycin effectively reduce coronary restenosis. We report here a novel role of this drug in protection against ischemia/reperfusion (I/R) injury. Adult male ICR mice were treated with rapamycin (0.25 mg/kg, IP) or volume-matched DMSO (solvent for rapamycin). The hearts were subjected to 20 min of global ischemia and 30 min of reperfusion in Langendorff mode. The blocker of mitochondrial KATP channel, 5-hydroxydecanoate (5-HD, 100 microM) was given 10 min before ischemia. Infarct size in the DMSO treated group was 28.2 +/- 1.3% and was reduced to 10.1 +/- 2.8% in the rapamycin-treated mice (64% decrease, P < 0.001). 5-HD blocked the protective effect (infarct area 32.2 +/- 1.8%, P < 0.001 vs. rapamycin). The infarct limiting effect of rapamycin was not associated with improved recovery of ventricular function. We further examined the effect of rapamycin in protection against necrosis and apoptosis in adult cardiomyocytes subjected to simulated ischemia and reoxygenation. Myocytes treated with rapamycin in doses from 25-100 nM demonstrated significantly lower trypan blue-positive necrotic cells and TUNEL-positive apoptotic nuclei, supporting the protective role of drug in the intact heart. These data suggest that rapamycin induces potent preconditioning-like effect against myocardial infarction through opening of mitochondrial KATP channels. We propose that rapamycin may be a novel therapeutic strategy to limit infarction, apoptosis, and remodeling following I/R injury in the heart.     

Human immunodeficiency virus has an aspartic-type protease that can be inhibited by pepstatin A.

The protease encoded by the human immunodeficiency virus (HIV) processes the viral gag and gag-pol protein precursor by posttranslational cleavage. In this study we have demonstrated by site-specific mutagenesis (Asp----Thr) and by pepstatin A inhibition that the recombinant HIV protease is an aspartic-type protease. Furthermore, incubation of HIV-infected H9 cells with pepstatin A inhibited part of the intracellular processing of the HIV gag protein yet had no apparent toxicity on HIV-infected cells during 48 hr of incubation.     

Short-term intestinal ischemia-reperfusion alters intestinal motility that can be preserved by xanthine oxidase inhibition

While the effects of transient intestinal ischemia on mucosa have been well investigated, less is known about its effect on motor function. An experimental study was designed to investigate the effects of ischemia–reperfusion (I/R) on intestinal motility and intestinal muscular microcirculation. Wistar albino rats were divided into four groups: (1) baseline, (2) sham operation, (3) I/R, and (4) I/R with allopurinol pretreatment. Ischemia was induced by clamping the superior mesenteric artery (SMA) for 10 min. Gastroanal transit time (GATT) was measured with serial x-rays after instillation of barium sulfate to the stomach. Intestinal muscular microcirculation was evaluated by determining the number of carbon-perfused intestinal muscular microvessels (CPIMM). I/R prolonged GATT and decreased CPIMM significantly (P < 0.01). Pretreatment with allopurinol prevented prolongation of GATT and returned the number of CPIMM to the level of sham treatment (P < 0.01). In conclusion, reperfusion after 10 min of SMA ischemia alters intestinal motility. The no-reflow phenomenon plays an important role in this alteration of motility. Administration of allopurinol before reperfusion preserves intestinal motility by preventing the occurrence of no-reflow phenomenon.