缺血后处理对保护皮瓣的作用机制研究

目的：缺血后处理已经在心、肾等器官上广泛应用,进行相关研究进一步探究缺血后处理对皮瓣有否保护作用。方法：健康成年新西兰大白兔,分为3组。A组为给予缺血后处理;B组为再灌注前5min给予A2A阻滞剂SCH58261＋缺血后处理。C组,直接应用微血管夹阻断腹壁浅血管持续缺血6h后,恢复正常血供。分别进行中性粒细胞浸润,MPO含量和皮瓣存活率检测。结果：新西兰大白兔完全存活。B、C组相比较,中性粒细胞计数以及MPO含量也未见统计学差别（P〉0.005）。实验组皮瓣存活面积比较,B与C相比较,无统计学意义（P〉0.005）,但是A与B、C相比较,上述指标两两之间都有统计学意义差别（P〈0.005）。结论：缺血后处理对皮瓣再灌注损伤有保护作用,该作用可能和A2A受体性质有关。     

心肌缺血/再灌注损伤分子信号保护机制的研究进展

缺血/再灌注损伤是一种常见的病理生理改变,近些年来,随着对其机制的大量研究,缺血/再灌注损伤的分子信号保护机制有了许多新的进展.腺苷激动腺苷2A受体(A2AAR),通过Gs蛋白-cAMP信号轴抑制与再灌注相关的炎症反应起保护作用.激活的阿片受体是通过抗细胞凋亡自身激酶信号路径的相互作用来减少再灌注损伤的.缺血后处理的机制也可能涉及到内源性腺苷释放增加.     

缺血后处理激活自噬保护皮瓣机制研究

目的:缺血后处理皮瓣在临床上已经运用,开始相关研究探究缺血后处理对皮瓣保护机制。方法:健康成年新西兰大白兔,分为3组。A组为给予缺血后处理;B组为再灌注前5mi n给予自噬阻滞剂3-甲基腺嘌呤10μl+缺血后处理。C组,直接应用微血管夹阻断腹壁浅血管持续缺。6h后再灌。各组分别进行自噬指标Becl i n1、LC3免疫组化和皮瓣存活率检测。结果:新西兰大白兔完全存活。B、C组相比较,自噬Becl i n1、LC3免疫组化染色阳性细胞面积变化未见统计学差别(P>0.005)。实验组皮瓣存活面积比较,B与C相比较,无统计学意义(P>0.005),但是A与B、C相比较,上述指标两两之间都有统计学意义差别(P<0.005)。结论:缺血后处理对皮瓣再灌注损伤有保护作用,该作用可能和自噬激活有关。     

阿魏酸钠对移植皮瓣缺血再灌注损伤保护的实验研究

目的：通过建立大鼠皮瓣移植损伤的动物模型,观察阿魏酸钠对皮瓣存活率的影响。方法：利用H＆E染色分析皮瓣的损伤程度,利用免疫组化检测皮瓣组织中COX-2及HO-1的表达水平,利用ELISA法检测皮瓣组织中MPO、MDA、NO的含量以及外周血中TNF-α的表达水平。结果：在移植皮瓣缺血再灌注损伤模型中,相比于生理盐水处理组,阿魏酸钠处理可显著提高皮瓣的存活率,同时上调皮瓣组织中HO-1的表达水平,抑制COX-2通路的活化。在阿魏酸钠的作用下,皮瓣组织的MPO、MDA的含量明显下降,同时NO的合成增加,阿魏酸钠可显著抑制外周血中TNF-α的表达水平。结论：阿魏酸钠对移植皮瓣缺血再灌注损伤具有明显的保护作用,其作用机制与减少炎症反应,抑制氧化应激损伤密切相关。     

缺血后处理对大鼠移植肝缺血再灌注损伤的保护作用

目的探讨在体条件下缺血后处理对大鼠移植肝缺血再灌注损伤的保护作用及其可能机制。方法采用SD大鼠原位肝移植模型,供肝冷保存时间100min,无肝期控制于18min以内,60只雄性健康SD大鼠随机分为3组,对照组12只,缺血再灌注损伤组和后处理组各24只。对照组开腹后仅游离肝周韧带;缺血再灌注损伤组受体大鼠供肝切除前仅以肝素化生理盐水经门静脉灌注;后处理组供肝植入后完全再灌注前,给予多次短暂复灌复停作为缺血后处理。缺血再灌注损伤组、后处理组受体一半（6只）于再灌注后2h留取血液及肝组织,另一半（6只）于再灌注后6h留取肝组织。对照组于关腹后相应时间留取血液及肝组织。各组分别检测肝功能,采用酶联免疫吸附法测定血清肿瘤坏死因子Or．和中性粒细胞弹性蛋白酶。根据酶促反应原理,利用分光光度仪测定肝脏谷胱甘肽过氧化物酶、丙二醛、髓过氧化物酶、超氧化物歧化酶。肝组织HE染色后光镜下观察组织学变化。结果缺血再灌注损伤组和后处理组血清肝功能指标、炎性细胞因子水平及肝组织过氧化物含量均高于对照组（P〈0．05）,而后处理组较缺血再灌注损伤组则明显低（P〈0．05）;缺血再灌注损伤组和后处理组肝组织抗氧化酶活力显著低于对照组（P〈0．05）,而后处理组较缺血再灌注损伤组则明显高（P〈0．05）。结论缺血后处理对大鼠移植肝的缺血再灌注损伤有明显的保护作用。提高组织的抗氧化能力和降低炎性细胞因子水平可能是缺血后处理保护作用的机制之一。     

舒洛地特在NF-κB介导皮瓣缺血/再灌注损伤中保护作用的机制研究

目的探讨舒洛地特对大鼠皮瓣缺血/再灌注(ischemia-reperfusion,I/R)损伤保护作用的机制。方法建立皮瓣I/R损伤大鼠模型,将实验大鼠随机分为3组,每组24只。假手术组(A组):不进行灌注干预;I/R组(B组):术前1 h,于腹腔注射生理盐水10 ml/kg,进行I/R处理;舒洛地特组(C组):注入同等量稀释的舒洛地特注射液(10 mg/kg)进行I/R处理。采用SPSS21.0统计软件,对检测皮瓣组织中NF-κB的含量进行数据处理;7 d后,采用图像分析皮瓣的存活率。结果免疫组化提示,B组比C组、A组的表达明显增强,且阳性部位主要是血管壁细胞及中性粒细胞。C组再灌注后,NF-κB活性受到抑制,中性粒细胞浸润及组织水肿程度较B组明显改善。采用Western blot检测NF-κB提示,B组C组A组;7 d后,皮瓣的存活率检测提示,A组C组B组。结论舒洛地特在皮瓣缺血/再灌注损伤时能有效保护皮瓣,其机制可能与抑制NF-κB表达及降低局部炎性反应有关。     

腺苷A_1受体激动剂后处理对兔心肌缺血-再灌注损伤的影响

目的 探讨腺苷A1受体激动剂(2-氯环戊腺苷,CCPA)后处理对兔心肌缺血-再灌注损伤的保护作用.方法 32只兔随机均分为四组:假手术组(S组,开胸后仅行左冠状动脉套线而不阻断160min)、缺血-再灌注组(IR组,行左冠状动脉前降支阻断40 min,再灌注120 min)、缺血后处理组(lPC组,结扎左冠状动脉前降支40 min,再通30 s,结扎30 s,重复3次,再灌注120 min)和CCPA后处理组(APC组,结扎左冠状动脉前降支40 min,开放左冠状动脉1 min内予以静推CCPA100 μg/kg,冉灌注120 min).分别于左冠状动脉前降支阻断前20 min(T1)、左冠状动脉前降支阻断20 min(T2)、左冠状动脉前降支阻断40 min(T3)、心肌再灌注1 h(T4)和心肌再灌注2 h(T5)抽取颈内动脉血测定血清心肌肌钙蛋白I(cTnI)含量.再灌注末抽血离心测定超氧化物歧化酶(SOD)、丙二醛(MDA),测定心肌梗死面积.结果 和IR组相比,IPC组和APC组再灌注各个时间点cTnI均降低(P<0.05);IPC组和APC组梗死面积均小于IR组(P<0.05);IPC组和APC组血清中sOD的活性高于IR组,MDA的含量低于IR组(P<0.05).结论 腺苷A1受体激动剂后处理具有类似缺血后处理的心肌保护作用.其机制可能是通过减少氧自山基的生成,增强心肌抗氧化能力.     

阿霉素预处理替代缺血预处理提供鼠皮瓣缺血耐受的实验研究

目的探讨阿霉素预处理提供鼠皮瓣缺血耐受的可能性及其作用机制。方法健康成年SD大鼠24只,雌雄各半,体重250～300 g,随机分为A、B、C 3组(n=8)。于各组大鼠腹部制备以腹壁浅血管-神经束为蒂、大小为6 cm×3 cm的岛状皮瓣,A组不作处理;B组用微血管夹阻断腹壁浅血管血流10 min,松开后再灌注10 min,反复4次;C组经腹壁浅静脉推注阿霉素(1 mg/kg)。24 h后于皮瓣蒂部夹闭腹壁浅血管4 h,再灌注2 h,制备缺血再灌注损伤模型。术后观察大鼠存活情况,于缺血再灌注损伤后0、8、12、24、30 h各组取皮瓣检测丙二醛(malonyldiadehyde,MDA)和超氧化物歧化酶(superoxide dismutase,SOD)含量;于缺血再灌注损伤后7 d测量皮瓣成活率后处死大鼠,取皮瓣行组织学观察。结果实验中共5只大鼠死亡,其中A、B组各1只,C组3只,均给予补充。缺血再灌注损伤后7 d,A组皮瓣成活率为10.10%±0.43%,小于B组91.63%±1.76%及C组92.75%±1.48%,差异均有统计学意义(P<0.05);B组与C组比较,差异无统计学意义(t=0.29,P=0.77)。缺血再灌注损伤后0 h 3组间MDA和SOD含量比较,差异均无统计学意义(P>0.05);8 h后各时间点A组与B、C组比较,差异均有统计学意义(P<0.05),B组与C组比较差异无统计学意义(P>0.05)。组织学观察示,A组炎性细胞浸润较B、C组明显,纤维增生减弱;B组与C组皮瓣组织学改变相似。结论阿霉素预处理可以提供鼠皮瓣缺血耐受,保护皮瓣减轻缺血再灌注损伤,其机制可能与诱导内源性保护物质的产生有关。     

热应激预处理对皮瓣缺血再灌注损伤的影响及机制

目的探索减轻皮瓣缺血再灌注损伤的有效措施。方法采用大鼠腹部岛状皮瓣,制作活体原位热缺血模型,观察热缺血再灌注后皮瓣的成活率、皮瓣组织形态学改变,检测皮瓣超氧化物歧化酶(SOD)活性、丙二醛(MDA)含量、HSP_(70)表达。结果缺血8h 后再灌注,实验组皮瓣存活率明显高于对照组;与对照组相比,实验组皮瓣组织中 SOD 活性较高而 MDA 水平较低;电镜显示,实验组皮瓣毛细血管内膜较完整,细胞肿胀轻,线粒体结构较稳定。结论热应激预处理,能减轻缺血再灌注对皮瓣的损伤,对缺血再灌注皮瓣具有保护作用,其机制可能与热应激预处理抗自由基损害作用及维护细胞膜结构稳定有关。     

热应激预处理对皮瓣缺血再灌注损伤的影响及机制

目的　探索减轻皮瓣缺血再灌注损伤的有效措施。方法　采用大鼠腹部岛状皮瓣,制作活体原位热缺血模型,观察热缺血再灌注后皮瓣的成活率、皮瓣组织形态学改变,检测皮瓣超氧化物歧化酶（ Ｓ Ｏ Ｄ） 活性、丙二醛（ Ｍ Ｄ Ａ） 含量、 Ｈ Ｓ Ｐ７ ０ 表达。结果　缺血８ｈ 后再灌注,实验组皮瓣存活率明显高于对照组;与对照组相比,实验组皮瓣组织中 Ｓ Ｏ Ｄ 活性较高而 Ｍ Ｄ Ａ 水平较低;电镜显示,实验组皮瓣毛细血管内膜较完整,细胞肿胀轻,线粒体结构较稳定。结论　热应激预处理,能减轻缺血再灌注对皮瓣的损伤,对缺血再灌注皮瓣具有保护作用,其机制可能与热应激预处理抗自由基损害作用及维护细胞膜结构稳定有关。     

Ischemia postconditioning protects dermal microvascular endothelial cells of rabbit epigastric skin flaps against apoptosis via adenosine A2a receptors

Background: It has been shown that endogenous adenosine-induced by ischemia postconditioning attenuates apoptosis in recent studies; however, they focus only on parenchymal cells. The detailed mechanism has not been clearly clarified in any research and the subtype of adenosine receptors involved remains unknown. In our study, dermal microvascular endothelial cells (DMECs) are used to explore the role of adenosine A_2a receptor in the anti-apoptotic effects of ischemic postconditioning.

Material and methods: The epigastric skin flaps of rabbits were elevated. After 4?h of ischemia, the flaps were either abruptly reperfused or postconditioned by six cycles of brief reperfusion (15s) and re-ischemia (15s). Adenosine A2a receptor agonist (CGS-21680) and antagonist (ZM-241385) were used separately in other groups. The apoptosis-related proteins and adenosine A2a receptors were determined by immunohistochemical staining. Then apoptosis index was calculated by TUNEL.

Results: Ischemia/reperfusion caused severe damages in DMECs of flaps as demonstrated by an increase in apoptosis index and an increase in expressions of apoptosis-related proteins, which can be significantly attenuated by IPC treatment or exposure to a selective adenosine A_2a receptor agonist (all p values <.05). Meanwhile, the anti-apoptosis effects of IPC can be blocked by a selective adenosine A_2a receptor antagonist. Statistical analysis revealed that the increase of apoptosis index closely correlated inversely with the relative increase of adenosine A_2a receptors (p?Conclusions: Ischemia postconditioning protects DMECs of rabbit skin flap against apoptosis via activation of adenosine A_2a receptors.     

腺苷促进猪横行腹直肌骨皮瓣成活的实验研究

目的人研究腺苷对猪横行腹直肌肌皮瓣成活率的影响。方法 横行腹直肌肌皮瓣以左侧腹壁下去共血血管,肌蒂宽６ｃｍ,皮瓣面积８ｃｍ×３０ｃｍ。２０头猪分为生理盐水对照组和１ｍｇ、２ｍｇ、５ｍｇ腺苷注射实验组,掀起此瓣前从腹壁上动脉注射不同剂量的腺苷和生理盐水。术后７天注射荧光素,以模片法记录腹直肌同侧皮瓣、对侧皮瓣和整个皮瓣的成活率。结果 ２ｍｇ和５ｍｇ腺苷注射级,肌皮瓣成活率明显高于生理盐水对照组（Ｐ〈     

早期反复短时缺血训练对皮瓣成活的影响及其机制研究

目的观察早期反复短时缺血训练对皮瓣成活面积、血管内皮生长因子(vascularendothelialgrowthfactor,VEGF)及微血管密度(microvesseldensity,MVD)的影响。方法取日本大耳白兔72只,随机选取64只为实验组,在其背部两侧对称位置建立蒂在上端的皮瓣区,皮瓣范围为4cm×3cm。随机选一侧为训练皮瓣组(A组),另侧为对照皮瓣组(B组),其余8只背部两侧相同部位标记后不作处理,为空白对照组(C组)。术后即对A组皮瓣蒂部进行反复短时缺血训练。分别于术后1~8d每天随机取实验组8只断蒂,检测A、B组各时间点皮瓣成活面积;并于各时间点检测A、B组皮瓣和C组相应部位皮肤组织内的VEGF相关系数和MVD值。对A组皮瓣成活面积VEGF相关系数和MVD值行相关分折。结果术后动物全部成活,无感染、死亡,活动情况无明显变化。A组3~8d皮瓣成活面积较B组高,差异有统计学意义(P<0.05)。A、B组各时间点VEGF表达及MVD值均较C组高;A组1~6dVEGF表达高于B组,差异有统计学意义(P<0.01);且A组各时间点MVD值高于B组,差异有统计学意义(P<0.05)。相关分折见A组皮瓣成活面积与MVD、MVD与VEGF成正相关,时间点对应关系为n与n-2;相关系数分别为0.850和0.801。结论早期反复短时缺血训练可提高皮瓣成活面积,利于早期断蒂,其机制可能为训练使VEGF表达增强,进而增加皮瓣微血管密度,加速皮瓣血供重建。     

Preconditioning of the distal portion of a rat random-pattern skin flap.

It has been shown that preconditioning either by proximal pedicle clamping or by pedicle intravascular drug administration, for example with adenosine, can improve flap survival. These methods, however, are not well suited to random-pattern flap transfer in the clinical setting. The aim of this study was to evaluate clinically applicable preconditioning methods for random-pattern flaps. Eighteen male Sprague-Dawley rats were used. Bipedicled dorsal skin flaps (2 x 8cm) containing panniculus carnosus were elevated. In the ischaemic preconditioning group the cranial pedicle was clamped for 20min, followed by 40min reperfusion before the cranial pedicle was cut, producing a caudally based random-pattern flap. In the pharmacologic preconditioning group adenosine was locally injected in the cranial half of the flap before the cranial pedicle was cut. In the control group saline was locally injected instead of adenosine and the pedicle was cut in the same manner. Flap survival area was evaluated at day 7. Flap survival area in both preconditioning groups was significantly higher than in the control group (P<0.05). Both preconditioning methods can improve random-pattern flap survival in rats. These methods may prove useful in the clinical setting.     

腺苷后处理对大鼠心肌缺血再灌注时血清IL-10和TNF-α浓度的影响

目的 探讨腺苷后处理对大鼠心肌缺血再灌注时血清IL-10和TNF-α浓度的影响.方法 雄性SD大鼠24只,体重180～250 g,随机分为4组(n=6):假手术组(S组)、缺血再灌注组(IR组)、缺血后处理组(IP组)和腺苷后处理组(AP组).IR组、IP组和AP组结扎冠状动脉左前降支30 min后恢复再灌注.IP组缺血30 min时进行再灌注30 s缺血30 s,循环3次,然后再灌注120 min;AP组缺血30 min时静脉输注腺苷40 μg·kg-1·min-1,剂量1.5 mg/kg,然后再灌注120 min.于缺血前(基础状态)、缺血30 min、再灌注30、120 min时记录HR、SP和DP.再灌注120 min时采集动脉血样,测定血清IL-10和TNF-α的浓度.采集血样后,取心肌组织,测定MDA含量及心肌梗死面积,光镜下观察心肌病理学结果.结果 与S组比较,IR组HR、SP和DP降低,IP组和AP组SP降低,IR组、IP组和AP组血清IL-10、TNF-α浓度和心肌MDA含量升高,心肌梗死面积增加(P<0.05);与IR组比较,IP组和AP组HR、SP和DP升高,血清TNF-α浓度和心肌MDA含量降低,心肌梗死面积减小,血清IL-10浓度升高(P<0.05);IP组和AP组上述指标差异无统计学意义(P>0.05).IP组和AP组心肌病理学损伤程度轻于IR组.结论 腺苷后处理可促进IL-10生成,抑制TNF-α生成,从而减轻大鼠心肌缺血再灌注损伤.     

Platelet glycoprotein IIb/IIIa receptor antagonist (abciximab) inhibited platelet activation and promoted skin flap survival after ischemia/reperfusion injury

BACKGROUND: Evidence has shown that platelets play an important role in the pathogenesis of flap failure. Employing a rat inferior epigastric artery skin flap as a flap reperfusion injury model, we investigated whether platelet activation was involved in the skin flap failure and whether administration of abciximab (ReoPro, chimeric 7E3 Fab) could decrease platelet activation/aggregation and promote flap survival. METHODS: Normal saline and abciximab (0.06 mg/kg; 0.2 mg/kg; 1 mg/kg) were injected intravenously into skin flaps 30 min before reperfusion and 1 h after reperfusion (each subgroup n = 6). Platelet activation as demonstrated by P-selectin (CD62P) was analyzed by flow cytometry. P-selectin expression on flap vessels was detected by immunohistochemical staining. Platelet aggregation was induced with adenosine diphosphate (ADP). Laser Doppler flowmetry monitored tissue perfusion. The surviving area was evaluated 7 days postoperatively. RESULTS: CD62P progressively increased after reperfusion. The peak CD62P occurred after reperfusion for 12 h. Immunohistochemical staining showed CD62P significantly deposited on the endothelium after reperfusion. Administration of abciximab (1 mg/kg) effectively improved flap survival rate (P = 0.003), significantly decreased ADP-induced platelet aggregation (P < 0.001), and suppressed CD62P expression on blood platelets (P = 0.002) and its deposition on the flap vessels. CONCLUSION: Abciximab promotion of skin flap survival is due to blocked platelet activation/aggregation and decreased activated-platelet deposition on the vascular endothelium. Thus, administration of a platelet glycoprotein IIb/IIIa receptor antagonist such as abciximab may save the skin flap from reperfusion injury after a long period of ischemia.     

The effect of antagonism of adenosine A1 receptor against ischemia and reperfusion injury of the liver

BACKGROUND: Adenosine is known to exert protective roles in hepatic ischemia and reperfusion injury, while all adenosine receptors do not play the cytoprotective roles. We have tested our hypothesis that blockage of adenosine binding to A(1) receptor by its antagonist, KW3902 [8-(noradamantan-3-yl)-1,3-dipropylxanthine] attenuates hepatic ischemia-reperfusion injury. METHODS: Adult female beagle dogs underwent a 2 h total hepatic vascular exclusion (THVE) with a venovenous bypass. Nontreated animals that underwent THVE with a venovenous bypass alone were used as the control (Group CT, n=6). KW3902 was given to the animals by continuous intraportal infusion for 60 min before ischemia at a dose of 1 microg/kg/min (Group KW, n=6). Two wk survival, hemodynamics, hepatic tissue blood flow (HTBF), liver function, energy metabolism, cAMP concentration, and histopathological findings were studied. RESULTS: Two wk animal survival was significantly improved in group KW compared with that in group CT (group CT: 16.7% versus group KW: 83.3%). HTBF, liver function, and hepatic adenine nucleotide concentration were remarkably better in group KW than group CT. In addition, cAMP concentration in group KW was maintained significantly higher than group CT. Histopathological examination revealed preservation of hepatic architecture and suppression of neutrophil infiltration into hepatic tissue in group KW. CONCLUSION: Administration of adenosine A(1) receptor antagonist before ischemia attenuates hepatic ischemia-reperfusion injury. To elicit the beneficial effect of adenosine against ischemia and reperfusion injury of the liver, it is important to oppose adenosine A1 receptor activation.     

Protective effect of a nuclear factor-kappaB inhibitor on ischemia-reperfusion injury in a rat epigastric flap model

We examined whether nuclear factor-kappa B (NF-kappaB) activation was involved in the ischemia-reperfusion (I/R) injury in a rat skin flap model and whether administration of pyrrolidine dithiocarbamate (PDTC), a NF-kappaB inhibitor, could improve flap viability. Eighty-four Sprague-Dawley rats were divided into control group (n = 28), I/R group (n = 28), and PDTC-treated group (n = 28). An abdominal skin flap (4 x 5 cm) was elevated and subjected to 10 hours of ischemia in both the I/R group and the PDTC-treated group. A bolus of PDTC (300 mg/kg) was infused 5 minutes before reperfusion, followed by a second dose during the first 30 minutes of reperfusion in the PDTC-treated group. Flap tissues were assessed by electrophoretic mobility shift assay at 1, 2, 3, and 6 hours of reperfusion, and myeloperoxidase activity and neutrophil infiltration were assessed at 12 hours of reperfusion. The viability of flaps was assessed 7 days postoperatively. NF-kappaB was activated after reperfusion in the I/R group and displayed peak activity at 1 and 3 hours of reperfusion. In the PDTC-treated group, NF-kappaB activity was significantly reduced at 1, 2, and 6 hours of reperfusion. Myeloperoxidase activity was significantly decreased, and little neutrophil infiltration could be observed. In the PDTC-treated group, the survival of flaps was 86.88 +/- 13.63%, which was significantly greater than the I/R group, in which only 19.20 +/- 7.52% of the flap survived. NF-kappaB is activated during reperfusion in a rat skin flap I/R model. Administration of PDTC can significantly improve flap survival by regulating the early activation of NF-kappaB and suppressing neutrophil infiltration within the flap.