携Sialyl Lewis^X超声微泡靶向探查缺血心肌的炎症分子“印记”

目的探讨应用靶向超声分子成像探查心肌缺血再灌注损伤炎症“印记”的可行性。方法采用“亲和素-生物素”桥接法构建携唾液酸化路易斯（Sibyl Lewis^X）靶向超声微泡（MBsLex）和同型对照微泡（MBc）。10只心肌缺血再灌注小鼠随机先后注入MBsLex和MBc（间隔30min）,分别于注入5min后行心肌对比超声检查,测量心肌缺血区和非缺血区的声强度（Ⅵ）。结果对比超声图像显示MBsLex组缺血区心肌造影见显著增强,Ⅵ值高达23．52±1．08,而在MBc组缺血区心肌造影仅见轻度增强,Ⅵ缸为9．81±0．41,两者之间差异有统计学意义（P〈0．05）。但无论MBsLex组还是MBc组,缺血区心肌Ⅵ值均明显高于非缺血区心肌Ⅵ值（P〈0．05）。两组非缺血区心肌之间Ⅵ值未见明显差异。结论应用携sLex超声微泡行对比超声能够靶向探查心肌缺血再灌注损伤的炎症“印记”。     

Effect of some free radical scavengers on reperfusion induced arrhythmias in the isolated rat heart

The possible role of oxygen free radicals in the development of reperfusion arrhythmias was investigated using a 10-min period of coronary ligation followed by reperfusion in the isolated rat heart. Superoxide dismutase (5 to 20 u/ml) glutathione (10(-5) to 10(3)M) and ascorbic acid (10(-4) to 5 X 10(-4) M) when given before coronary ligation attenuated the development of reperfusion arrhythmias. Mannitol (2 X 10(-2)M) and catalase (100 and 300 u/ml) did not have any significant effect on reperfusion arrhythmias when given alone but they did potentiate the antiarrhythmic effect of superoxide dismutase. Glutathione, and a combination of superoxide dismutase, catalase and mannitol also reduced the incidence of reperfusion induced ventricular fibrillation when given just before reperfusion. By perfusing hearts with ferricytochrome C it was possible to show an increased reduction of ferricytochrome C during the first minute of reperfusion which could be prevented by the addition of superoxide dismutase. These results provide evidence that oxygen free radicals are produced and may be important in the genesis of reperfusion induced arrhythmias in the isolated rat heart.     

Involvement of endothelin/ nitric oxide balance in hepatic ischemia/ reperfusion injury

Introduction: Endothelin (ET) and nitric oxide (NO) act as opponents in the regulation of the hepatic microcirculation. During ischemia/reperfusion (I/R) ET levels are increased, whereas no rise in NO levels is observed. This imbalance may be responsible for microcirculatory disturbances. The aim of this study was to restore the delicate ET/NO balance to maintain the integrity of the hepatic microcirculation and to reduce I/R injury. Methods: Ischemia was induced by crossclamping of the hepatoduodenal ligament for 30 min with portal decompression using a splenocaval shunt (56 Wistar rats, 200–250 g). Sham operation, ischemia and treatment groups with the endothelin receptor antagonist (ERA) bosentan (1 mg/kg body weight i.v.) and the NO donor l-arginine (400 mg/kg body weight i.v.) were performed. For assessment of the microcirculation, sinusoidal perfusion rate, diameters of sinusoids and postsinusoidal venules, leukocyte endothelium interactions and velocity of free-flowing leukocytes were investigated by means of in vivo microscopy 30–90 min after reperfusion. Local hepatic tissue pO₂ was measured prior to ischemia, 30 min and 60 min after reperfusion and aspartate aminotransferase (AST)/alanine aminotransferase (ALT) levels were investigated 2 h and 6 h after reperfusion. Results: After ischemia, sinusoidal and venular diameters were reduced to 76% and 85%, respectively, of sham operation group values (P<0.05), but were maintained at baseline in ERA (98/102%) and NO (102/105%) groups (P<0.05). Increased postischemic leukocyte sticking in sinusoids (144%) and venules (435%) was reduced by therapy to 110/253% (ERA) and 111/ 324% (NO), respectively (P<0.05). Perfusion rate was increased to 93% and 94% compared with 82% in the ischemia group (P<0.05). Concomitant with the improved microcirculation in therapy groups, local hepatic tissue pO₂ was improved 30 min after reperfusion in the ERA (11.0 mmHg) and the l-arginine group (11.5 mmHg) relative to the ischemic group (6.9 mmHg) (P<0.05). In addition, postischemic AST/ALT increase was reduced by therapy. Conclusion: Our results indicate that maintenance of ET/NO balance by blocking ET receptors, as well as providing a NO donor, protects the liver microcirculation and reduces hepatic I/R injury. Received: 14 August 1998 Accepted: 13 October 1998     

Ischemic preconditioning enhances donor lung preservation in the rabbit

Objective: Ischemic preconditioning achieved by brief periods of ischemia followed by reperfusion before a prolonged period of ischemia, is well known to reduce myocardial damage. We investigated whether ischemic preconditioning of the lung could also attenuate ischemia-reperfusion injury following pulmonary preservation. Methods: Transient ischemia of the right lung was achieved in rabbits (n=4 in each group) by occluding the main bronchus and pulmonary artery, followed by reperfusion according to a protocol that differed between study groups: group 1 (control), 45 min ventilation; group 2, 30 min ventilation, 5 min ischemia and 10 min reperfusion; group 3, three periods of 5 min ischemia and 10 min reperfusion; group 4, five periods of 3 min ischemia and 6 min reperfusion. Donor lungs were then flushed with a crystalloid solution followed by inflated storage at 37°C for 2 h. The function of the right lung was assessed during reperfusion for 2 h with homologous, diluted and deoxygenated blood in an isolated, pressure-limited, and room-air ventilated model. Results: Significant differences (P<0.0001) were observed between groups 1 and 2 vs. groups 3 and 4 in veno–arterial oxygen pressure gradient (29±6 and 24±6 mm Hg vs. 124±24 and 132±14 mm Hg, respectively), and in weight gain (88±13 and 98±13% vs. 44±9 and 29±3%, respectively) after 1 h of reperfusion, and in wet-to-dry weight ratio (15.5±1.5 and 14.3±0.4 vs. 10.1±1.6 and 9.0±0.8, respectively) at the end of reperfusion. No significant differences in any of these parameters were observed between group 1 vs. group 2 neither between group 3 vs. group 4. Conclusions: These data suggest: (1) That 15 min, but not 5 min of transient ischemia prior to pulmonary preservation can significantly reduce edema in the lung graft upon reperfusion, thus improving oxygenation capacity and (2) although not significant, this beneficial effect seems to be slightly better with more repetitive periods of transient ischemia. Further research is warranted to investigate whether ischemic preconditioning in the human organ donor may become a new strategy to protect lung tissue during a planned ischemic event as in pulmonary transplantation.     

复温对大鼠移植肝脏抗氧自由基损伤的研究

目的　探讨复温对抗氧自由基损伤,保护移植肝脏的作用。方法　建立下腔静脉内置管法大鼠自体原位肝移植模型。在再灌流前对移植肝脏用不同温度进行复温,动态观察肝组织中脂质过氧化物（ＬＰＯ） 含量和超氧化物歧化酶（ＳＯＤ） 活性的变化,并同步观察肝细胞光镜和透视电镜下的形态学变化。结果　再灌流后与复温后比较ＬＰＯ有显著升高,ＳＯＤ 有明显下降（ Ｐ＜０ ．０１） 。用３６ ℃复温组与其他各复温组比较可明显减少ＬＰＯ的升高和ＳＯＤ 的下降（Ｐ＜ ０．０５）;同步病理也证明用３６ ℃复温可明显减轻肝细胞的损伤。结论　复温可间接抑制氧自由基的产生,减轻再灌流损伤,能够达到保护肝细胞的作用。     

人参皂甙Rb1减轻大鼠脊髓缺血再灌注损伤的实验研究

目的在整体水平探讨人参皂甙Rb1对脊髓缺血再灌注损伤(spinal cord ischemiareperfusion injury,SCII)的治疗作用。方法 Sprague-Dawley(SD)大鼠72只,随机分为假手术组、对照组(SCII+安慰剂)和实验组(SCII+人参皂甙Rb1),采用腹主动脉夹闭法建立SCII模型。应用Basso-Beattie-Bresnahan(BBB)评分系统评价神经功能,HE染色观察病理组织结构和细胞形态改变,原位末端脱氧核苷酸转移酶标记(the in situ terminal deoxynucleotidyl transferase-mediateddUTP nick end-labeling technique,TUNEL)方法检测细胞凋亡情况。结果人参皂甙Rb1干预可以减轻脊髓缺血再灌注损伤导致的后肢功能障碍。HE染色显示人参皂甙Rb1干预可减轻神经元受损程度。TUNEL检测显示假手术组很少有细胞凋亡,对照组的神经细胞凋亡率最高,实验组与对照组比较可显著减少细胞凋亡率,差异有统计学意义(P<0.05)。结论人参皂甙Rb1可改善大鼠神经功能,减轻SCII导致的神经元受损,减少脊髓细胞凋亡。     

大鼠移植胰腺冷缺血再灌注后细胞凋亡及其调控基因的研究

目的探讨胰腺移植再灌注后胰腺细胞凋亡发生的过程,以及Bax、Bcl2及Fas等调控基因的表达。方法65只SD大鼠随机分成7组假手术组,冷缺血2h组,冷缺血2h再灌注1、3、6、9、12h组。电镜观察胰腺组织的病理变化;采用缺口末端标记法(TUNEL)检测凋亡细胞;采用免疫组织化学方法检测胰腺组织中Bax、Bcl2及Fas蛋白的表达。结果胰腺移植后早期即可观察到细胞凋亡,凋亡的高峰期为再灌注后3h,凋亡指数(AI)为(95±29)%,P<001,再灌注6h组细胞凋亡有所减少,AI为(57±17)%,P<001,再灌注9h及12h组,AI分别为(36±16)%及(33±14)%,P<005。假手术组与冷缺血2h组均未见Bax、Fax蛋白表达。冷缺血再灌注1h组Bax( )、Fas( ),未见Bcl2蛋白表达;至冷缺血再灌注3h组Bax及Fas表达均增强,分别为Bax( )、Fas( ),以后各组表达有所下降。Bcl2蛋白在假手术组、冷缺血2h组及冷缺血再灌注1h组均未见表达,冷缺血再灌注3h及以后各组表达为( )。结论细胞凋亡是胰腺移植后的早期事件,Bax、Fas基因可能促进了胰腺细胞的凋亡,而Bcl2基因可能抑制细胞凋亡。     

初始灌注液对离体低温保存大鼠肝脏的影响

目的 探讨缺血再灌注过程中初始灌注液对离体低温保存大鼠肝脏的影响。方法采用离体大鼠肝脏低温缺血保存再灌注模型90例,分别选择UW液、HC-A液和乳酸林格液作为不同的初始灌注液,观察大鼠肝脏在低温保存0、3、6、12、24 h后再灌注流出液中ALT、AST、LDH和ET的水平,同时比较3组之间肝脏细胞形态和细胞凋亡。结果 使用HC-A液作为初始灌注液的大鼠肝脏再灌注流出液中ALT、AST、LDH和ET水平较其他两组低(P<0.05),肝脏形态和细胞凋亡的发生3组差异无显著性。另外,上述指标均受低温保存时间的影响。结论 初始灌注液可影响离体低温保存大鼠肝脏的质量,细胞凋亡可能参与了肝脏的缺血再灌注损伤。     

17-β-雌二醇对大鼠肝脏缺血再灌注损伤的保护作用及其机制

目的 探讨17-β-雌二醇对雄性大鼠肝脏缺血再灌注(I／R)损伤的保护作用及其机制。方法 采用大鼠部分肝脏缺血再灌注损伤模型，将健康雄性SD大鼠96只随机分成两组：A组(缺血再灌注组)，B组(17-β-雌二醇处理组)。每组分别随机取6只于缺血前、肝脏再灌注后1h、2h、4h、1d、3d、5d、7d时检测血清谷丙转氨酶(ALT)、谷草转氨酶(AST)、乳酸脱氢酶(LDH)和肿瘤坏死因子(TNF-α)水平，并进行统计学处理。结果 除缺血前和再灌注7d外A组动物在相应时点ALT、AST、LDH、TNF-α水平均高于B组，且A组动物肝功能恢复正常时间(与缺血前相比)迟于B组。结论 17-β-雌二醇对肝脏缺血再灌注损伤有显著的保护作用，并可缩短病程，其作用机制可能与17-β-雌二醇降低肝脏I／R时血清TNF-α水平有关。     

三七总皂甙对大鼠肝脏低温保存再灌注期间肝细胞凋亡的影响

目的　研究三七总皂甙 (PNGS)对大鼠肝脏低温保存再灌注期间肝细胞凋亡的影响及其机制。方法　采用大鼠离体肝脏再灌注模型 (IPRL) ,用Fura 2法测定低温保存 2h后肝细胞内钙离子浓度 ;经乳酸林格氏液 (LR)低温保存 2 4h的肝脏再灌注 30min后进行肝脏功能检测、氧自由基代谢产物、肝细胞凋亡、Bcl 2蛋白表达及形态学观察。LR和DMEM液中加入不同浓度PNGS。结果　大鼠肝细胞内钙离子浓度、MDA、SOD、肝细胞凋亡及Bcl 2蛋白表达阳性率等项指标各实验组明显好于对照组 (P <0 0 1) ,PNGS对大鼠肝细胞凋亡的保护作用显示出剂量依赖性 ,在 2 0 0～ 6 0 0mg范围内随剂量增加保护作用随之增强 (P <0 0 1) ,在 80 0～ 10 0 0mg范围内虽有增强 ,但无明显差别 (P >0 0 5 )。结论　PNGS减轻了大鼠肝脏在低温保存再灌注期间肝细胞凋亡 ,可能与通过抑制钙超载、抗氧自由基损伤、提高Bcl 2蛋白表达作用有关。