内皮素对缺氧肝脏的损伤作用及降钙素基因相关肽的拮抗效应

本实验在大鼠肝脏原位缺氧灌流模型上,发现10^(-8)mol/L内皮素(ET)灌流,不仅强烈收缩门静脉血管,而且明显加重组织缺氧损伤:加重肝脏水肿、增加组织脂质过氧化物生成和溶酶体酶漏出。应用10^(-8)mol/L降钙素基因相关肽(CGRP)与ET同时灌流,有效地拮抗了ET对缺氧肝脏的损伤作用。

蛋白激酶C在肝细胞缺氧预处理中的作用

目的:研究蛋白激酶C(PKC)在肝细胞缺氧预处理中的作用, 方法:建立体外肝细胞缺氧预处理模型,应用PKC抑制剂白屈菜季铵碱(chelerythrine chloride,CHE)和激动剂豆蔻酸佛波酰乙酯(phorobol12-myristate13-acetate,PMA),通过检测PKC磷酸化活性,细胞存活率,同时在透射电镜下观察肝细胞超微结构改变,研究PKC的作用,对相关数据进行统计学处理。结果:和缺氧复氧组的PKC磷酸化活性(710.5±78.8)fkat/g比较,缺氧预处理组的PKC磷酸化活性(1823.7±2682)fkat/g和PKC激动剂组的PKC磷酸化活性(2541.2±326.5)fkat/g显著增高(P<0.01),肝细胞结构损伤改变较小;和缺氧预处理组比较,PKC抑制剂组相应指标呈相反的变化,PKC磷酸化活性(1088.0±89.3)fkat/g(P<0.01)。结论:肝细胞缺氧预处理细胞保护作用中,PKC通路起到至关重要的作用。

内源性Fe^(2+)在鼠肝缺血缺氧再给氧后脂质过氧化中的作用

内源性Ｆｅ２＋在鼠肝缺血缺氧再给氧后脂质过氧化中的作用刘振宅（天津医科大学生物医学工程系，天津３０００７０）许多病理过程都伴有器官和组织的局部缺血，缺血缺氧后再给氧时脂质过氧化作用急剧增强，导致组织不可逆损伤和坏死。本文建立了鼠肝缺血缺氧再给氧模型，...

黑色素瘤缺乏因子2在缺氧复氧损伤介导的肝细胞焦亡中的作用

目的探讨黑色素瘤缺乏因子2(AIM2)在缺氧复氧损伤介导的肝细胞焦亡中的作用。方法(1)采用缺氧复氧法干预L02细胞以构建肝脏缺血再灌注损伤体外模型。检测未建模L02细胞(空白对照组)以及缺氧后复氧1 h、3 h、6 h、12 h、24 h的L02细胞的活性、细胞焦亡率以及焦亡相关蛋白[半胱氨酸天冬氨酸蛋白酶(Caspase)-1、白细胞介素(IL)-1β、IL-18]、AIM2蛋白的表达水平。(2)将L02细胞分为空白对照组、缺氧复氧模型组、缺氧复氧+si-AIM2组、缺氧复氧+si-NC组。缺氧复氧+si-AIM2组、缺氧复氧+si-NC组细胞分别转染si-AIM2、si-NC后进行缺氧6h/复氧培养12 h的干预;缺氧复氧模型组细胞仅进行缺氧培养6 h、复氧培养12 h,空白对照组细胞在常氧条件下等时长培养。检测各组细胞活性、焦亡率及焦亡相关蛋白表达水平。结果(1)与空白对照组相比,复氧6 h后L02细胞活性开始降低,复氧3 h后L02细胞焦亡率开始上升(P<0.05);复氧3 h、6 h、12 h、24 h后L02细胞活性依次降低而焦亡率依次升高(均P<0.05)。与空白对照组相比,复氧3 h后L02细胞AIM2蛋白的表达水平开始增加,复氧6 h后L02细胞Caspase-1、IL-1β、IL-18表达水平开始升高(均P<0.05);复氧24 h后L02细胞以上蛋白的表达水平高于2个或2个以上不同复氧时间组(均P<0.05)。(2)与缺氧复氧模型组和缺氧复氧+si-NC组比较,缺氧复氧+si-AIM2组细胞活性升高,且焦亡率、Caspase-1和IL-1β的表达水平均降低(P<0.05),而缺氧复氧模型组和缺氧复氧+si-NC组之间差异并无统计学意义(P>0.05);缺氧复氧+si-AIM2组IL-18的表达水平亦低于缺氧复氧+si-NC组(P<0.05)。结论AIM2参与缺氧后复氧诱导的L02细胞焦亡;干扰AIM2基因的表达可能通过抑制Caspase-1、IL-1β、IL-18的表达水平来改善缺氧后复氧引起的L02细胞焦亡。

异丙酚和咪达唑仑对大鼠肝脏缺氧复氧损伤影响的比较

为对比观察异丙酚和咪达唑仑对大鼠肝脏缺氧复氧损伤的影响,将成年健康Wistar大鼠24只随机分为4组:对照组(A组)、缺氧复氧组(B组)及咪达唑仑或异丙酚预处理组(C组和D组),每组6只。采用酶联免疫吸附法检测大鼠肝组织8-异前列腺素F2α(8-iso-PGF2α)水平;硝酸还原法测定其一氧化氮合酶(NOS)活力和NO含量。结果表明,缺氧复氧后,B组肝组织中8-iso-PGF2α水平明显升高,而NOS活力和NO含量则明显降低,与A组比较差异有显著意义(P<0·05);C、D两组与B组相比,肝组织中8-iso-PGF2α水平明显下降,而NOS活力和NO含量明显上升,差异亦有显著意义(P<0·05);D组的肝组织8-iso-PGF2α含量明显低于C组,而其NOS活力和NO含量明显高于C组(P<0·05)。结论:咪达唑仑也像异丙酚一样对大鼠肝脏缺氧复氧损伤具有明显的保护作用,但其保护效应不如异丙酚。

Angiostatin基因治疗人肝癌裸鼠移植瘤的实验研究

目的:研究Angiostatin基因治疗对人肝癌裸鼠皮下移植瘤的抑制作用及其相关机理。方法:使用人原发性肝癌细胞株SMMC-7721建立人肝癌裸鼠皮下移植瘤动物模型,质粒用脂质体DOTAP介导转染细胞。将荷瘤裸鼠随机分为两组,分别注射质粒PcDNA3、Angiostatin/PcDNA3,观察两组动物的肿瘤生长曲线,检测肿瘤的Angiostatin、VEGF、HIF-1α表达和微血管密度(MVD),利用TUNEL染色法行原位细胞凋亡分析。结果:Angiostatin基因治疗在早期具有抑制肿瘤生长的作用,大约1周后肿瘤以更快的速度生长并迅速赶上空质粒对照组肿瘤;Angiostatin基因治疗组的肿瘤组织中有An-giostatin的局部高表达,MVD(24.8±2.8)低于空质粒对照组(30.2±4.1)(P〈0.05)。肿瘤组织中HIF-1α蛋白局部高表达,VEGF表达高于空质粒对照组,细胞凋亡指数(2.87±0.48)高于空质粒对照组(1.55±0.43)(P〈0.01)。结论:Angiostatin基因治疗对人肝癌裸鼠皮下移植瘤的生长具有一定的抑制作用,肿瘤对Angiostatin基因治疗可以产生耐受性。

缺氧诱导因子-1α及其靶基因在人肝癌HepG2细胞中的表达和意义

缺氧诱导因子-1（HIF-1）存在于大多数实体肿瘤中，是肿瘤细胞维持氧平衡的重要的转录调节子。HIF-1包含α和β两个亚基（HIF-1α和HIF-1β），其中HIF-1α是主要的功能亚基，对HIF-1的转录活性起关键作用。缺氧条件下，HIF-1α被运输到核内，与HIF—1β形成二聚体，通过与靶基因上的缺氧反应元件（HRE）结合而促进靶基因转录，其蛋白质产物发挥多种生物学功能，如参与肿瘤血管的形成与发展，肿瘤细胞能量代谢，肿瘤细胞增殖与存活等。

银杏提取物对新生大鼠缺氧缺血性肝损伤的治疗作用

目的 评价银杏提取物 (extract of ginkgo biloba,EGB)对新生大鼠缺氧缺血性肝损伤的治疗作用。 方法 将 4 6只 SD新生大鼠分为 4组 :缺氧缺血组 (n=30 ) ,EGB治疗组 (n=2 4 ) ,生理盐水组 ,假手术组 (n=6 ) ,建立新生大鼠缺氧缺血性脑损伤 (HIBD)模型 ,再给氧后 2、2 4、4 8、72、16 8h后分别进行免疫组织化学及组织 HE染色 ,观察不同时间肝组织粘附分子 1(ICAM- 1)的表达、中性粒细胞浸润和肝细胞的形态学变化 ,并腹腔注射梯度剂量的 EGB治疗 ,以生理盐水和段手术作对照。 结果 肝微血管内皮细胞 ICAM- 1的表达于再给氧后 2 4 h免疫反应开始增加 [(5 2 .5±17.0 ) % ],4 8h达高峰 [(76 .5± 11.9) % ](H =2 3.9,P<0 .0 1) ,16 8h恢复正常 [(6 .9± 4 .3) % ],同时中性粒细胞浸润也随之增加 ,在时程上与 ICAM- 1表达同步。 EGB组以 5 0 mg/ (kg· d)的剂量为最佳 ,当再给氧 4 8h后 ICAM- 1免疫阳性内皮细胞数 [(17.5± 14 .9) % ]及中性粒细胞浸润比同时间缺氧缺血组明显降低、肝细胞损伤减轻 (H =2 0 .8,P<0 .0 1;D=87,P<0 .0 5 )。 结论 ICAM- 1与缺氧缺血后肝组织中性粒细胞浸润密切相关 ,5 0 m g/ (kg· d)的 EGB对新生大鼠缺氧缺血性肝损伤可能有一定保护作用。

Resveratrol attenuates oxidative stress and histological alterations induced by liver ischemia/reperfusion in rats

AIM： To investigate the effects of resveratrol on liver ischemia/reperfusion （I/R） injury in rats. METHODS： A total of 40 male Sprague-Dawley rats weighing 240-290 g were randomized into four groups of ten： （1） controls： data from unmanipulated animals; （2） sham group： rats subjected to the surgical procedure, except for liver I/R, and given saline; （3） I/R group： rats underwent liver ischemia for 45 rain followed by reperfusion for 45 rain; （4） I-R/Resveratrol group： rats pretreated with resveratrol （10 umol/L, iv）. Liver tissues were obtained to determine antioxidant enzyme levels and for biochemical and histological evaluation. RESULTS： Plasma aminotransferase activities were higher in the I/R group than in the I-R/Resveratrol group. Malondialdehyde levels and the hepatic injury score decreased, while superoxide dismutase, catalase, and glutathione peroxidase levels increased in group 4 compared to group 3. In group 4, histopathological changes were significantly attenuated in resveratroltreated livers. CONCLUSION： These results suggest that resveratrol has protective effects against hepatic I/R injury, and is a potential therapeutic drug for ischemia reperfusionrelated liver injury.

Isoflurane preserves energy balance in isolated hepatocytes during in vitro anoxia/reoxygenation

AIM: To investigate the protective effect of isoflurane on energy balance in isolated hepatocytes during in vitro anoxia/reoxygenation, and to compare isoflurane with halothane. METHODS: Hepatocytes freshly isolated from fed rats were suspended in Krebs-Henseleit buffer, and incubated in sealed flasks under O2/CO2 or N2/CO2 (95%/5%, V/V) for 30 or 60 min, followed by 5 or 10 min of reoxygenation, with an added volatile anesthetic or not. ATP, ADP, and adenosine monophosphate in hepatocytes were determined by high performance liquid chromatography, and energy charge was calculated. RESULTS: During 30 min of anoxia, the energy charge and total adenine nudeotide steadily increased with the isoflurane dose from 0 to 2 minimum alveolar anesthetic concentration (MAC), then decreased from 2 to 3 MAC. In short incubations (30-35 min) at 1 MAC isoflurane, energy charge modestly decreased during anoxia, which was partially prevented by isoflurane and completely reversed by reoxygenation, and total adenine nudeotide did not decrease. In long incubations (60-70 min), both energy charge and total adenine nudeotide greatly decreased during anoxia, with partial and no reversal by reoxygenation, respectively. Isoflurane partly prevented decreases in both energy charge and total adenine nudeotide during anoxia and reoxygenation. In addition, 1 MAC isoflurane obviously increased ATP/ADP, which could not be changed by 1 MAC halothane. CONCLUSION: Isoflurane partially protects isolated hepatocytes against decreases in both energy charge and total adenine nudeotide during short (reversible) or long (irreversible) anoxia.

Protection against hepatic ischemia/reperfusion injury via downregulation of toll-like receptor 2 expression by inhibition of Kupffer cell function

AIM： To elucidate the mechanism of liver protection by inhibition of Kupffer cells （KCs） function.METHODS： All the animals were randomly divided into three groups. Blockade group （gadolinium chloride solution （GdCl3） injection plus ischemia/reperfusion （I/R） injury）：GdCl3 solution was injected once every 24 h for 2 d via the tail vein before I/R injury. Non-blockade group （saline solution injection plus I/R injury）： saline instead of GdCl3 as a control was injected as in the blockade group. Sham group： saline was injected without I/R injury. Liver samples were collected 4 h after blood inflow restoration. The blockade of the function of KCs was verified by immunostaining with an anti-CD68 mAb. Toll-like receptor2 （TLR2） was immunostained with a goat antimouse polydonal anti-TLR2 antibody. Membrane proteins were extracted from the liver samples and TLR2 protein was analyzed by Western blot. Portal vein serum and plasma were taken respectively at the same time point for further detection of the levels of tumor necrosis factor-α （TNF-α） and alanine aminotransferase （ALT）, an indicator of liver function.I/R injury via downregulation of theexpression of TLR2.RESULTS： Compared to non-blockade group, CD^68＋ cells significantly reduced in blockade group （OPTDI, optical density integral）： 32.97±10.55 vs 185.65±21.88, P〈0.01） and the liver function impairment was relieved partially （level of ALT： 435.89±178.37 U/L vs 890.21±272.91 U/L,P〈0.01）. The expression of TLR2 protein in blockade group significantly decreased compared to that in non- group（method of immunohistochemistry, OPDTI： 75.74±17.44 vs 170.58±25.14, P〈0.01; method of Western blot, A value： 125.89±15.49 vs 433.91±35.53, P〈0.02）. The latter correlated with the variation of CD68 staining （r = 0.745,P〈0.05）. Also the level of portal vein TNF-α decreased in blockade group compared to that in non-blockade group （84.45±14.73 ng/L vs 112.32±17.56 ng/L, P〈0.05）, butwas still higher than that in sham group （84.45±14.73 ng/L vs 6.07±5.33 ng/L, P〈0.01）.CONCLUSION： Inhibition of the function of KCs may protect liver against I/R injury via downregulation of the expression of TLR2.

Dynamical changing patterns of glycogen and enzyme histochemical activities in rat liver graft undergoing warm ischemia injury

AIM:To investigate the changing patterns of glycogen and enzyme histochemical activities in rat liver graft under a different warm ischemia time (WIT) and to predict the tolerant time limitation of the liver graft to warm ischemia injury. METHODS: The rats were randomized into five groups, WIT was 0,15,30,45,60 min, respectively, and histochemical staining of liver graft specimens was observed. The recovery changes of glycogen and enzyme histochemistry activities were measured respectively 6 and 24 h following liver graft implantation. RESULTS: The activities of succinic dehydrogenase, cytochrome oxidase, apyrase (Mg++-ATPase) and content of glycogen were decreased gradually after different WIT in a time-dependent manner. The changes were significant when WIT was over 30 min. CONCLUSION: Hepatic injury is reversible within 30 min of warm ischemia injury. Glycogen and enzyme histochemistry activities of liver grafts and their recovery potency after reperfusion may serve as criteria to evaluate the quality of liver grafts.

Gender differences in hepatic ischemic reperfusion injury in rats are associated with endothelial cell nitric oxide synthase-derived nitric oxide

AIM: This study was designed to examine the hypothesis that gender differences in I/R injury are associated withendothelial cell nitric oxide synthase (eNOS)-derived nitric oxide (NO).METHODS: Wistar rats were randomized into seven experimental groups (12 animals per group). Except for the sham operated groups, all rats were subjected to total liver ischemia for 40 min followed by reperfusion. All experimental groups received different treatments 45 min before the laparotomy. For each group, half of the animals (six) were used to investigate the survival; blood samples and liver tissues were obtained in the remaining six animals after 3 h of reperfusion to assess serum NO, alanine aminotransferase (ALT) and TNF-α levels, liver tissuemalondialdehyde (MDA) content, and severity of hepatic I/R injury.RESULTS: Basal serum NO levels in female sham operated (FS) group were nearly 1.5-fold of male sham operated (MS) group (66.7±11.0 μmol/L vs 45.3±10.1μmol/L, P＜0.01). Although serum NO levels decreased significantly after hepatic I/R (P＜0.01, vs sham operated groups), they were still significantly higher in female rat (F) group than in male rat (M) group (47.8±8.6 μmol/L vs 23.8±4.7 μmol/L, P＜0.01). Serum ALT and TNF-α levels, and liver tissue MDA content were significantly lower in F group than in M group (370.5±46.4 U/L, 0.99±0.11 μg/L and 0.57±0.10 μmol/g vs668.7±78.7 U/L, 1.71±0.18 μg/Land 0.86±0.11 μmol/g, respectively, P＜0.01). I/R induced significant injury to the liver both in M and F groups (P＜0.01 vs sham operated groups). But the degree of hepatocyte injury was significantly milder in F group than in M group (P＜0.05 and P＜0.01). The median survival time was six days in F group and one day in M group. The overall survival rate was significantly higher in F group than in M group (P＜0.05). When compared with male rats pretreated with saline (M group), pretreatment of male rats with 17-β- estradiol (E2) (M+E2 group) significantly increased serum NO levels and significantly decreased serum ALT and TNF-α levels, and liver tissue MDA content after I/R (P＜0.01).The degree of hepatocyte injury was significantly decreased and the overall survival rate was significantly improved in M+E2 group than in M group (P＜0.01 and P＜0.05). TheNOS inhibitor Nw-nitro-L-arginine methyl ester (L-NAME) treatment could completely abolish the protective effects of estrogen in both male and female rats. CONCLUSION: The protective effects afforded to female rats subjected to hepatic I/R are associated with eNOSderived NO.

Mild hypothermia protects liver against ischemia and reperfusion injury

AIM: To determine whether mild hypothermia could protect liver against ischemia and reperfusion injury in pigs. METHODS: Twenty-four healthy pigs were randomly divided into normothermia, mild hypothermia and normal control groups. The experimental procedure consisted of temporary interruption of blood flow to total hepatic lobe for different lengths of time and subsequent reperfusion. Hepatic tissue oxygen pressure (PtiO2) and aspartate aminotransferase (AST) values were evaluated, and ultrastructural analysis was carried out for all samples. RESULTS: Serum AST was significantly lower, and hepatic PtiO2 values were significantly higher in the mild hypothermia group than in the normothermia group during liver ischemia-reperfusion periods (P= 0.032, P= 0.028). Meanwhile, the histopathologic injury of liver induced by ischemia-reperfusion was significantly improved in the mild hypothermia group, compared with that in the normothermia group. CONCLUSION: Mild hypothermia can protect the liver from ischemia-reperfusion injury in pigs.

Hepatic injury induced by carbon dioxide pneumoperitoneum in experimental rats

AIM： To observe the hepatic injury induced by carbon dioxide pneumoperitoneum in rats and to explore its potential mechanism.METHODS： Thirty healthy male SD rats were randomly divided into control group （n = 10）, 0 h experimental group （n = 10） and 1 h experimental group （n = 10） after sham operation with carbon dioxide pneumoperitoneum. Histological changes in liver tissue were observed with hematoxylineosin staining. Liver function was assayed with an automatic biochemical analyzer. Concentration of malonyldialdehyde （MDA） and activity of superoxide dismutase （SOD） were assayed by colorimetry. Activity of adenine nucleotide translocator in liver tissue was detected with the atractyloside-inhibitor stop technique. Expression of hypoxia inducible factor-1 （HIF-1） mRNA in liver tissue was detected with in situ hybridization.RESULTS： Carbon dioxide 60 min could induce liver pneumoperitoneum for injury in rats. Alanine aminotransferase and aspartate aminotransferase were 95.7 ± 7.8 U/L and 86.8 ± 6.9 U/L in 0 h experimental group, and 101.4 ± 9.3 U/L and 106.6 ±8.7 U/L in 1 h experimental group. However, no significant difference was found in total billirubin, albumin, and pre-albumin in the three groups. In 0 h experimental group, the concentration of MDA was 9.83 ±2.53 μmol/g in liver homogenate and 7.64 ± 2.19 μmol/g in serum respectively, the activity of SOD was 67.58±9.75 nu/mg in liver and 64.47 ± 10.23 nu/mg in serum respectively. In 1 h experimental group, the concentration of MDA was 16.57±3.45 μmol/g in liver tissue and 12.49 ±4.21 μmol/g in serum respectively, the activity of SOD was 54.29 ±7.96 nu/mg in liver tissue and 56.31 ±9.85 nu/mg in serum respectively. The activity of ANT in liver tissue was 9.52 ± 1.56 in control group, 6.37± 1.33 in 0 h experimental group and 7.2 8±1.45 （10^-9 mol/min per gram protein） in 1 h experimental group, respectively. The expression of HIF-1 mRNA in liver tissue was not detected in control group, and its optical density difference value was 6.14±1.03 in 0 h experimental group and 9.51 ± 1.74 in 1 h experimental group, respectively. CONCLUSION： Carbon dioxide pneumoperitoneum during the sham operation can induce hepatic injury in rats. The probable mechanisms of liver injury include anoxia, ischemia reperfusion and oxidative stress. Liver injury should be avoided during clinical laparoscopic operation with carbon dioxide pneumoperitoneum.

Protective effects of ischemic preconditioning and application of lipoic acid prior to 90 min of hepatic ischemia in a rat model

AIM： To compare different preconditioning strategies to protect the liver from ischemia/reperfusion injury focusing on the expression of pro- and anti-apoptotic proteins. Interventions comprised different modes of ischemic preconditioning （IP） as well as pharmacologic pretreatment by α-lipoic acid （LA）. METHODS： Several groups of rats were compared： sham operated animals, non-pretreated animals （nt）, animals receiving IP （10 rain of ischemia by clamping of the portal triad and 10 min of reperfusion） prior to sustained ischemia, animals receiving selective ischemic preconditioning （IPsel, 10 min of ischemia by selective clamping of the ischemic lobe and 10 rain of reperfusion） prior to sustained ichemia, and animals receiving 500 1μmol α-LA injected i.v. 15 min prior to the induction of 90 min of selective ischemia. RESULTS： Cellular damage was decreased only in the LA group. TUNEL-positive hepatocytes as well as necrotic hepatocyte injury were also decreased only by LA（19 ± 2 vs 10 ± 1, P〈 0.05 and 29 ± 5 vs 12 ± 1, P 〈 0.05）. Whereas caspase 3- activities in liver tissue were unchanged, caspase 9- activity in liver tissue was decreased only by LA pretreatment （3.1 ± 0.3 vs 1.8 ± 0.2, P 〈 0.05）. Survival rate as the endpoint of liver function was increased after IP and LA pretreatment but not after IPsel. Levels of lipid peroxidation （LPO） in liver tissue were decreased in the IP as well as in the LA group compared to the nt group. Determination of pro- and anti-apoptotic proteins showed a shift towards anti-apoptotic proteins by LA. In contrast, both our IP strategies failed to influence apototic cell death. CONCLUSION： IP, consisting of 10 min of ischemia and 10 min of reperfusion, ischemia/reperfusion injury protects only partly against of the liver prior to 90 min of selective ischemia. IPsel did not influence ischemic tolerance of the liver. LA improved tolerance to ischemia, possibly by downregulation of pro-apoptotic Bax.