基于PI3K/Akt通路研究利拉鲁肽对2型糖尿病骨质疏松大鼠的作用

目的基于磷脂酰肌醇-3-激酶/丝苏氨酸蛋白激酶(phosphateidylinositol-3 kinase/serine-threonine kinase,PI3K/Akt)通路研究利拉鲁肽对2型糖尿病性骨质疏松(type 2 diabetic osteoporosis,T2DOP)大鼠的影响。方法高脂高糖、腹腔注射30mg/kg链脲佐菌素(STZ)并摘除卵巢建立T2DOP大鼠模型,将大鼠随机分为模型组、利拉鲁肽组、利拉鲁肽+LY294002组;正常饲养大鼠作为正常组,每组10只。大鼠体重,空腹血糖,股骨组织形态,血清中骨保护素(OPG)、细胞核因子KB受体活化因子配基(RANKL)水平,骨密度,股骨组织中磷酸化-PI3K(p-PI3K)、PI3K、磷酸化-Akt(p-Akt)、Akt蛋白水平进行比较。结果模型组大鼠体重、FBG,血清中RANKL水平升高(P0.05),血清中OPG水平、股骨组织骨密度,p-PI3K/PI3K、p-Akt/Akt蛋白水平降低(P0.05);而利拉鲁肽组大鼠体重、FBG,血清中RANKL水平降低(P0.05),血清中OPG水平、股骨组织骨密度,pPI3K/PI3K、p-Akt/Akt蛋白水平升高(P0.05);利拉鲁肽添加PI3K抑制剂LY294002后逆转利拉鲁肽症状。结论利拉鲁肽激活PI3K/Akt通路实现对T2DOP大鼠骨质疏松的保护。     

预输注青年大鼠血浆对老龄大鼠术后认知功能的影响及PI3K/Akt信号通路在其中的作用

目的评价预输注青年大鼠血浆对老龄大鼠术后认知功能的影响及磷脂酰肌醇3-激酶/丝氨酸苏氨酸蛋白激酶(PI3K/Akt)信号通路在其中的作用。方法 SPF级健康雄性老龄SD大鼠60只, 18月龄, 体重550～650 g, 采用随机数字表法分为4组(n=15):对照组(C组)、手术组(O组)、青年大鼠血浆组(P组)和PI3K抑制剂LY294002组(LY组)。P组和LY组尾静脉注射青年大鼠血浆100 μl, C组和O组尾静脉注射等容量生理盐水, 2次/周, 持续4周。O组、P和LY组大鼠在七氟烷麻醉下行单侧胫骨骨折内固定术。麻醉前LY组尾静脉注射PI3K抑制剂LY294002 0.3 mg/kg。术后3 d时行旷场实验评估大鼠自发活动能力, 然后行Morris水迷宫实验评估大鼠认知功能。行为学测试结束后处死大鼠, 分离海马组织, 采用Western blot法测定磷酸化PI3K(p-PI3K)、磷酸化Akt(p-Akt)、突触蛋白、突触素Ⅰ和突触囊泡蛋白的表达水平, 透射电镜下观察海马神经元超微结构并记录突触数量。结果 4组大鼠运动速度、路程以及旷场中心停留时间比较差异无统计学意义(P&g...     

PI3K/AKT通路和S1PR2在急性梗阻性胆管炎诱导大鼠全身炎症反应中的作用

目的研究急性梗阻性胆管炎(AOC)大鼠模型中外周血单个核细胞(PBMCs)中磷脂酰肌醇-3-羟激酶(PI3K)/AKT通路和鞘氨醇-1-磷酸受体2(S1PR2)的激活情况以及其对大鼠全身炎症反应的影响。方法①体外实验:分离和培养清洁级大鼠PBMCs,然后将其分为磷酸盐缓冲溶液对照组、单独PI3K抑制剂LY294002处理组、脂多糖处理组和脂多糖+LY294002处理组4组,收集各组细胞的上清液和总蛋白,检测细胞上清液中炎性因子肿瘤坏死因子-α(TNF-α)和白细胞介素-6(IL-6)水平以及细胞中PI3K、AKT磷酸化水平和S1PR2蛋白的变化。②体内实验:60只清洁级SD大鼠被随机分为假手术组、单独PI3K抑制剂LY294002处理组、AOC模型组及AOC模型+LY294002处理组4组,记录大鼠存活情况,检测大鼠血清中肝功能丙氨酸转氨酶(ALT)、门冬氨酸氨基转移酶(AST)和总胆红素(TBIL)水平及血清中TNF-α和IL-6的水平以及大鼠PBMCs中PI3K、AKT磷酸化水平和S1PR2蛋白的变化。结果①体外实验结果:脂多糖+LY294002处理组细胞上清液中TNF-α和IL-6水平均明显低于脂多糖处理组(P0.050),PI3K、AKT磷酸化水平和S1PR2的蛋白水平亦明显低于脂多糖处理组(P0.050)。②体内实验结果:AOC模型+LY294002处理组大鼠的生存率高于AOC模型组,血清中肝功能ALT、AST、TBIL和炎性因子TNF-α和IL-6水平均明显低于AOC模型组(P0.050),PI3K和AKT磷酸化水平及S1PR2蛋白表达水平也明显低于AOC模型组(P0.050)。结论抑制AOC模型大鼠中PBMCs中PI3K/AKT通路的活化,可降低S1PR2的表达,且能抑制AOC诱导的大鼠全身炎症反应。     

预先注射青年大鼠血浆对老龄大鼠脑缺血再灌注后认知功能障碍的影响及PI3K/Akt信号通路在其中的作用

目的评价预先注射青年大鼠血浆对老龄大鼠脑缺血再灌注后认知功能障碍的影响及磷脂酰肌醇3-激酶/丝氨酸苏氨酸蛋白激酶(PI3K/Akt)信号通路在其中的作用。方法 SPF级健康雄性老龄SD大鼠72只, 18月龄, 体质量600～650 g, 采用随机数字表法分为4组(n=18):对照组(C组)、脑缺血再灌注组(IR组)、预先注射青年大鼠血浆组(P组)和PI3K抑制剂LY294002组(LY组)。P组和LY组尾静脉注射青年大鼠血浆100 μl/次, C组和IR组尾静脉注射等容量生理盐水, 2次/周, 持续4周。然后IR组、P组和LY组在七氟烷麻醉下建立大鼠脑缺血再灌注损伤模型。麻醉前1 h时LY组尾静脉注射LY294002 0.3 mg/kg。再灌注后24 h时行神经功能缺损评分(Longa评分), 然后随机处死6只大鼠取脑组织, 测定脑梗死体积。再灌注29 d时行旷场试验评估大鼠自发活动能力和焦虑样行为, 再灌注30 d时行新物体识别实验评估大鼠认知功能。行为学测试结束后处死大鼠, 分离海马组织, 采用Western blot法测定磷酸化PI3K(p-PI3K)、磷酸化Akt(p-Akt)...     

PI3K/Akt/mTOR信号通路在依达拉奉减轻老龄大鼠术后认知功能障碍中的作用

目的评价磷脂酰肌醇3-激酶(PI3K)/丝氨酸-苏氨酸蛋白激酶(Akt)/哺乳动物雷帕霉素靶蛋白(mTOR)信号通路在依达拉奉减轻老龄大鼠术后认知功能障碍中的作用。方法健康雄性SD大鼠60只, 20月龄, 体质量600～700 g, 采用随机数字表法分为4组(n=15):对照组(C组)、手术组(O组)、依达拉奉组(E组)和PI3K抑制剂LY294002组(LY组)。O组、E组和LY组于3%七氟烷麻醉下行剖腹探查术。E组和LY组术前30 min时腹腔注射依达拉奉3 mg/kg, 同时LY组尾静脉注射LY294002 0.3 mg/kg。术后3 d时行旷场实验评估大鼠自发活动能力, 然后行Morris水迷宫实验评估大鼠认知功能。行为学实验结束后处死大鼠分离海马组织, 采用Western blot法测定磷酸化PI3K(p-PI3K)、磷酸化Akt(p-Akt)、磷酸化mTOR(p-mTOR)、突触素(SYP)和突触后致密蛋白95(PSD-95)的表达水平, 行高尔基染色记录海马CA1区神经元树突长度, 计算树突棘密度。结果 4组运动速度、路程及旷场中心停留时间比较差异无统计学意义(P>...     

补肾固本方对大鼠骨质疏松模型中PI3K/AKT/mTOR信号通路表达的调控研究

目的观察补肾固本方对去卵巢骨质疏松(osteoporosis,OP)大鼠骨组织中PI3K/AKT/mTOR信号通路的影响,探讨补肾固本方干预OP的作用机制。方法将100只SD大鼠随机分为5组:正常组(C组)、模型组(M组)、补肾固本方组(B组)、补肾固本方+PI3k受体特异性阻断剂LY294002组(B+L组)、PI3k受体特异性阻断剂LY294002组(L组),除正常组外,其余4组建立去卵巢大鼠OP模型。药物连续干预12周后,采用ELISA方法检测血清中E2、BGP、ALP水平,实时荧光定量聚合酶链式反应(Real-time PCR)检测各组股骨组织中LC3、Beclin1、caspase-9 mRNA的表达情况,蛋白质印迹法(Western blot)检测各组股骨组织中PI3K、AKT、mTOR蛋白的表达。结果补肾固本方可显著增高OP大鼠血清E2水平,降低BGP、ALP水平,显著上调LC3、Beclin1表达水平,降低caspase-9、PI3K、p-AKT、mTOR的表达;而上述变化能够被PI3k受体特异性阻断剂LY294002所阻断,且其差异具有统计学意义(P0.05)。结论补肾固本方减少去卵巢后大鼠OP的发生,其机制可能与抑制PI3K/AKT/mTOR信号通路及其下游基因蛋白表达有关。     

柚苷对髓核间充质干细胞生物学性能的影响及其相关机制

目的:探讨柚苷对人退变腰椎间盘来源髓核间充质干细胞(human nucleus pulposus-derived mesenchymal stem cell,h NPMSC)生物学性能的影响及其可能机制。方法:收集腰椎间盘突出症患者的退变髓核组织,分离培养h NPMSC并进行体外扩增。通过细胞形态学观察、细胞免疫表型检测及三系分化进行间充质干细胞的鉴定。取P3代hNPMSC分为对照组(正常培养基培养)、柚苷组(以含20μg/mL柚苷的培养基培养)和LY294002组(用含20μg/mL柚苷及PI3K/Akt信号通路抑制剂LY294002的培养基培养),培养6d后通过流式细胞仪检测细胞凋亡率,TUNEL荧光检测TUNEL染色阳性细胞率,Western Blot检测凋亡相关蛋白Caspase-3、Bcl-2和Bax及PI3K/Akt信号通路相关蛋白p-Akt、Akt和p53的表达,RT-PCR检测Ⅱ型胶原及蛋白多糖的m RNA表达。结果:来自人退变腰椎间盘髓核的原代细胞贴壁生长,呈不规则多边形,传代后以梭形为主;高表达干细胞相关阳性表面抗原分子CD73、CD90及CD105,低表达CD45及CD34;茜素红染色、油红O染色及甲苯胺蓝染色证实经诱导后可向骨、脂肪及软骨细胞分化,符合间充质干细胞的表型。与对照组比较,柚苷组细胞凋亡率、TUNEL染色阳性细胞率、p53、Caspase-3和Bax蛋白表达显著性下降,p-Akt及抗凋亡蛋白Bcl-2表达显著性增加(P0.05);LY294002干预后可以逆转这种改变(P0.05)。与对照组比较,柚苷组hNPMSC中Ⅱ型胶原及蛋白多糖的m RNA表达显著性增加;LY294002组中Ⅱ型胶原及蛋白多糖的m RNA表达较柚苷组显著性减少(P0.05)。结论:柚苷可通过激活PI3K/Akt信号通路减少细胞凋亡,促进hNPMSC向髓核细胞分化。     

miR-155靶向调节PIK3R1对类风湿关节炎大鼠模型PI3K/Akt/mTOR信号通路的影响

目的 探讨miR-155靶向调节PIK3R1对类风湿关节炎（rheumatoid arthritis,RA）大鼠PI3K/Akt/mTOR信号通路的影响。方法 SD大鼠随机分为对照组、模型组、miR-155 agomir组、miR-155 antagomir组、miR-155阴性对照组,诱导RA模型,分组处理后,观察关节症状,检测关节炎指数及后足趾容积;HE染色观察大鼠关节组织病理形态;使用试剂盒检测大鼠关节组织炎性因子IL-6、IL-17及IL-18水平;免疫印迹检测大鼠关节组织PI3K/Akt/mTOR信号通路蛋白表达;qRT-PCR实验检测大鼠关节组织miR-155及PIK3R1 mRNA水平;双荧光素酶报告基因实验检测miR-155对PIK3R1的靶向调控作用。结果 与对照组比较,模型组大鼠关节炎症状明显,关节炎指数、后足趾容积、关节组织炎性因子IL-6、IL-17及IL-18水平、关节组织p-PI3K/PI3K、p-Akt/Akt及p-mTOR/mTOR水平、关节组织miR-155水平明显升高（P＜0.05）,PIK3R1 mRNA水平明显降低（P＜0.05）。与模型组、miR-155阴性对照组比较,miR-155 antagomir组大鼠上述指标得到明显改善（P＜0.05）;miR-155 agomir组与miR-155 antagomir组趋势相反（P＜0.05）。结论 miR-155可靶向下调PIK3R1的表达,激活PI3K/Akt/mTOR信号,加重RA大鼠关节炎症损伤,下调miR-155表达,可抑制PI3K/Akt/mTOR信号激活及炎症反应发生发展,改善关节炎症状。     

异丙酚对肝缺血再灌注大鼠心肌损伤的影响及PI3K/Akt信号通路在其中的作用

目的 探讨异丙酚对肝缺血再灌注大鼠心肌损伤的影响及磷脂酰肌醇-3激酶/蛋白质丝氨酸苏氨酸激酶(PI3K/Akt)信号通路在其中的作用.方法 清洁级雄性SD大鼠102只,体重250～280g,采用结扎肝蒂30 min后再灌注的方法制备肝缺血再灌注模型.随机分为5组:假手术组(S组,n=6)仅分离肝门,不结扎;缺血再灌注组(I/R组,n=30)制备肝缺血再灌注模型;异丙酚组(P组,n=30)缺血前10 min股静脉注射异丙酚12 mg/k异的负荷剂量,随后以30 mg·kg-1·h-1的速率静脉输注直至处死;异丙酚+PI3K抑制剂组(P+LY组,n=18)缺血前10 min股静脉注射PI3K特异性抑制剂LY294002 1.5mg/kg(溶于二甲亚砜0.5 ml);溶剂对照组(P+DMSO组,n=18)缺血前10 min股静脉注射二甲亚砜0.5 ml.I/R组和P组于再灌注即刻、30、60、120和240 min(T1-55)时,P+LY组和P+DMSO组于T3-5时取6只大鼠,处死后快速取左心室壁心肌组织,测定总Akt(t-Akt)和磷酸化Akt(p-Akt),并于T3时测定Bcl-2的表达和心肌细胞凋亡情况,取肝左外叶组织,光镜下观察肝组织病理学结果.S组于T1相应时点处死大鼠,测定上述指标.结果 与S组比较,其余各组心肌p-Akt表达水平和心肌细胞凋亡率升高(P＜0.05),P+LY组心肌Bcl-2表达差异无统计学意义(P＞0.05),其他各组心肌Bcl-2表达均上调(P＜0.05);与I/R组比较,P组和P+DMSO组心肌p-Akt和Bcl-2表达上调,心肌细胞凋亡率降低(P＜0.05),P+LY组上述指标差异无统计学意义(P＞0.05);与P组比较,P+LY组心肌p-Akt和Bcl-2表达下调,心肌细胞凋亡率升高(P＜0.05),P+DMSO组上述指标差异无统计学意义(P＞0.05);各组心肌t-Akt表达比较差异无统计学意义(P＞0.05).P组和P+DMSO组肝组织病理学损伤较I/R组和P+LY组减轻.结论异丙酚可减轻大鼠肝缺血再灌注诱发心肌损伤,该作用与激活PI3K/Akt信号通路有关.     

基质细胞源性因子-1α/CXC趋化因子受体-4轴经PI3K/Akt通路对胃癌细胞CD133表达的调控作用

目的 观察胃癌中基质细胞源性因子-1α/CXC趋化因子受体-4(SDF-1α/CXCR4)轴经由PI3K/Akt信号通路对下游分子CD133表达及其活性的影响.方法 免疫细胞化学染色检测胃癌KATO -Ⅲ细胞株中CXCR4、Akt、p-Akt及CD133的表达.分别用SDF-1α、AMD3100及LY294002作用于胃癌KATO -Ⅲ细胞株,半定量酶链聚合反应(PCR)检测CXCR4 mRNA和CD133mRNA的表达变化,蛋白免疫印迹法检测CXCR4、Akt、p-Akt及CD133蛋白的表达变化.结果 免疫细胞化学染色证实KATO -Ⅲ细胞呈CXCR4、Akt、p-Akt及CD133阳性表达.SDF-1α组中,CXCR4蛋白(0.980±0.083)、p-Akt蛋白(0.770±0.071)及CD133蛋白(0.890±0.078)表达与对照组(0.750±0.042、0.680±0.038、0.720±0.034)比较明显增高(P＜0.05).与对照组(0.540±0.036、0.520±0.034)比较,CD133 mRNA(0.890±0.061)表达明显增高(P＜0.05).AMD3100组与对照组(0.750±0.042、0.680±0.038、0.720 ±0.034)比较,CXCR4蛋白(0.430±0.055)、p-Akt蛋白(0.350±0.050)及CD133蛋白(0.110±0.060)表达显著下降(P＜0.05).LY294002组中,p-Akt蛋白(0.100 ±0.033)、CD133蛋白(0.440±0.055)表达与对照组(0.680±0.038、0.720±0.034)比较显著下降(P＜0.05).同时,与对照组(0.540±0.036)比较,CD133mRNA(0.310±0.021)表达差异有统计学意义(P＜0.05).结论 刺激或抑制SDF-1α/CXCR4轴可经由PI3K/Akt信号通路上调或下调CD133表达.     

Vasopressor hormone response following mesenteric traction during major abdominal surgery

Background : We investigated the vasopressor hormone response following mesenteric traction (MT) with hypotension due to prostacyclin (PGI₂) release in patients undergoing abdominal surgery with a combined general and epidural anesthesia. Methods : In a prospective, randomized, placebo-controlled study we administered 400 mg ibuprofen (i.v.) in 42 patients scheduled for abdominal surgery. General anesthesia was combined with epidural anesthesia (T4-L1). Before as well as 5, 15, 30, 45, and 90 min after MT we recorded plasma osmolality, hemodynamics and measured 6-keto-PGFlα (stabile metabolite of PGI₂), TXB₂ (stabile metabolite of thromboxane A₂) active renin, and arginine vasopressin (AVP) plasma concentrations by radioimmunoassay. Catecholamine levels were assessed by high-pressure liquid chromatography (HPLC) with electrochemical detection. Results : Following MT, arterial hypotension occurred along with a substantial PGI₂ release. This was completely abolished by ibuprofen administration. Although plasma levels of 6-keto-PGF_1α (1133 (708) vs. 60 (3) ng/L, median (median absolute deviation), P=0.0001, placebo vs. ibuprofen) remained significantly elevated, blood pressure was restored within 30 min after MT in the placebo group. At the same point in time plasma concentrations of TXB² (164 (87) vs. 58 (1) ng/L, P=0.0001), epinephrine (46 (33) vs. 14 (6) ng/L, P=0.001), AVP (41 ± (18) vs. 12 (7) ng/L, P=0.0004), and active renin (27 (12) vs. 12 (4) ng/L, P = 0.001) were significantly higher in placebo-treated patients. Conclusion : Under combined general and epidural anesthesia arterial hypotension following MT due to endogenous PGI₂ release is associated with enhanced release of AVP, active renin, epinephrine and thromboxane A₂, presumably contributing to hemodynamic stability within 30 min after MT.     

A Teaspoon Pump for Pumping Blood with High Hydraulic Efficiency and Low Hemolysis Potential

Abstract: Virtually all blood pumps contain some kind of rubbing, sliding, closely moving machinery surfaces that are exposed to the blood being pumped. These valves, internal bearings, magnetic bearing position sensors, and shaft seals cause most of the problems with blood pumps. The original teaspoon pump design prevented the rubbing, sliding machinery surfaces from contacting the blood. However, the hydraulic efficiency was low because the blood was able to "slip around" the rotating impeller so that the blood itself never rotated fast enough to develop adequate pressure. An improved teaspoon blood pump has been designed and tested and has shown acceptable hydraulic performance and low hemolysis potential. The new pump uses a nonrotating "swinging" hose as the pump impeller. The fluid enters the pump through the center of the swinging hose; therefore, there can be no fluid slip between the revolving blood and the revolving impeller. The new pump uses an impeller that is comparable to a flexible garden hose. If the free end of the hose were swung around in a circle like half of a jump rope, the fluid inside the hose would rotate and develop pressure even though the hose impeller itself did not "rotate"; therefore, no rotating shaft seal or internal bearings are required.     

Microspheres Based Detoxification System: A New Method in Convective Blood Purification

Abstract: A variety of protein-bound or hydrophobic substances, accumulating as a result of pathologic conditions such as exogenous or endogenous intoxications, are removed poorly by conventional detoxification methods because of low accessibility (hemodialysis), insufficient adsorption capabilities (hemosorption), low efficiency (peritoneal dialysis), or economic limitations (high-volume plasmapheresis). Combining advantages of existing methods with microspheric technology, a module-based system was designed. Major operating parameters of the latter can be modified to allow for adjustment to individual clinical situations. An extracorporeal blood circuit including a plasmafilter is combined with a secondary high-velocity plasma circuit driven by a centrifugal pump. Different microspheric adsorbers can be combined in one circuit or applied in sequence. Thus, a prolonged treatment can be tailored using specially designed selective adsorber materials. Comparing this system with existing methods (high-flux hemodialysis, molecular adsorbent recycling system), results from our in vitro studies and animal experiments demonstrate the superior efficiency of substance removal.     

Tissue perfusion in relation to cardiac output during continuous positive-pressure ventilation and administration of propranolol or verapamil

Background : Our objective was to determine whether administration of propranolol or verapamil modifies the hemodynamic adaptation to continuous positive-pressure ventilation (CPPV), in particular the regional distribution of cardiac output (CO).
Methods : General hemodynamics and regional blood flows assessed by microsphere technique (15 (μm) were recorded in 16 anesthetized pigs during spontaneous breathing (SB) and CPPV with 8 cm H₂O end-expiratory pressure (CPPV8) before and after intravenous administration of propranolol (0.3 mg · kg⁻¹ followed by 0.15 mg · kg⁻¹ · h⁻¹, n=8) or verapamil (0.1 mg · kg⁻¹ followed by 0.3 mg · kg⁻¹ · h⁻¹, n=8).
Results : CPPV8 depressed CO by 25% without shifts in its relative distribution with the exception of a noteworthy increase in adrenal perfusion. Propranolol increased arterial blood pressure, and due to a fall in heart rate, CO dropped by 25%. The kidneys and, to a lesser extent, the splanchic region and central nervous system received increased fractions of the remaining CO at the expense of skeletal muscle flow. Similar patterns were seen during SB and CPPV8 such that the combination of propranolol and CPPV8 depressed CO by 50%. The circulatory effects of verapamil were less evident but myocardial perfusion tended to increase.
Conclusions : The combination of propranolol or verapamil with CPPV does not result in any specific hemodynamic interaction in anesthetized pigs, except that the combined effect of propranolol and CPPV may severely reduce CO.     

Bariatric Surgery in Some "Central and East-European (former Eastern bloc)"Countries - Current Status and Prediction for the Next Millennium

Background: Obesity is increasing globallly, including in the formerly "Eastern Bloc" countries. Methods: A survey was made of obesity and bariatric surgery. Results: In the 8 East and Central European countries studied, with total population 300 million, roughly 43% of the population was overweight (BMI 25-30), 23% obese (BMI > 30), with about 15 million people morbidly obese (BMI > 40). From 0-10 morbidly obese individuals/100,000/year undergo bariatric surgery. Conclusion: Most countries were found to provide inadequate treatment for obesity.The majority of the morbidly obese are not treated effectively. However, health-care awareness of obesity and bariatric surgeons are slowly increasing.     

Volatile anaesthetics reduce adhesion of blood platelets under low-flow conditions in the coronary system of isolated guinea pig hearts

Background : Inhibitory effects of volatile anaesthetics on platelet aggregation have been demonstrated in several studies. However, the influence of volatile anaesthetics on intracoronary platelet adhesion has not been elucidated so far.
Methods : Isolated hearts of guinea pigs were perfused with buffer in the absence or presence of volatile anaesthetics (0.5 and 1 MAC) at constant coronary flow rates of 5 ml/min for 25 min, then 1 ml/min for 30 min and again 5 ml/min for 10 min. Before, during and after low-flow perfusion, a bolus of human platelets was applied into the coronary system. To simulate thrombogenic conditions, 0.3 U/ml human thrombin was infused during low-flow perfusion and reperfusion. The number of platelets sequestered to the endothelium was calculated from the difference between coronary in- and output of platelets. The myocardial production of lactate and consumption of pyruvate and coronary perfusion pressure were also determined.
Results : At a flow rate of 5 ml/min only about 3% of the applied platelets did not emerge from the coronary system, in any group. In contrast, 13.1±1.2% (mean±SEM) of infused platelets became adherent in low-flow perfusion in the control group without anaesthetic. The adherence was reduced with each 1 MAC isoflurane (to 6.2±1.2%), sevoflurane (to 4.4±0.9%) or halothane (to 3.2±1.5%) (each P <0.05 vs. control). Volatile anaesthetic, 0.5 MAC, did not inhibit platelet adhesion to a statistically significant extent in any case. Perfusion pressure and metabolic parameters were not statistically different between the control and the hearts exposed to anaesthetics.
Conclusion : Volatile anaesthetics in a concentration of 1 MAC can reduce the adhesion of platelets in the coronary system under reduced flow conditions. This action does not arise from vasodilation or inhibition of ischaemic stress.     

Synergistic interaction between the effects of propofol and midazolam with fentanyl on phrenic nerve activity in rabbits

Background: It has been shown that the depressive effects of both propofol and midazolam on consciousness are synergistic with opioids, but the nature of their interactions on other physiological systems, e. g. respiration, has not been fully investigated. The present study examined the effect of propofol and midazolam alone and in combination with fentanyl on phrenic nerve activity (PNA) and whether such interactions are additive or synergistic. Methods: PNA was recorded in 27 anaesthetised and artificially ventilated rabbits. In three groups, propofol, fentanyl and midazolam were administered intravenously in incremental doses to construct dose-response curves for the depressant effects of each one on PNA. In another two groups, the effect of pretreatment with either fentanyl 1 μg · kg^?1 i. v. or midazolam 0.05 mg · kg^?1 i. v. on the effects of propofol and fentanyl respectively on PNA were studied. Results: Propofol and fentanyl caused a dose-dependent depression of PNA with complete abolition at the highest total doses of 16 mg · kg^?1 i. v. and 32 μg · kg^?1 i. v., respectively. In contrast, midazolam in incremental doses to a total of 0.8 mg · kg^?1 reduced mean PNA by 63%, but approximately 12% of PNA remained at a total dose as high as 6.4 mg · kg^?1. The mean ED₅₀s, calculated from dose-response curves, were 5.4 mg · kg^?1, 3.9 μg · kg^?1 and 0.4 mg · kg^?1 for propofol, fentanyl and midazolam, respectively. Initial doses of either fentanyl 1 μg · kg^?1 i. v. or midazolam 0.05 mg · kg^?1 i. v. acted synergistically with subsequent doses of either propofol or fentanyl to abolish PNA at total doses of 8 mg · kg^?1 and 8 μg · kg^?1, respectively. Conclusion: Fentanyl has a synergistic interaction with both propofol and midazolam on PNA and hence potentially on respiration.     

Influence of dopexamine hydrochloride on haemodynamics and regulators of circulation in patients undergoing major abdominal surgery

Background: Catecholaminergic support is often used to improve haemodynamics in patients undergoing major abdominal surgery. Dopexamine is a synthetic vasoactive catecholamine with beneficial microcirculatory properties. Methods: The influence of perioperative administration of dopexamine on cardiorespiratory data and important regulators of macro- and microcirculation were studied in 30 patients undergoing Whipple pancreaticduodenectomy. The patients received randomized and blinded either 2 μg · kg^?1 · min^?1 of dopexamine (n=15) or placebo (n=15, control group). The infusion was started after induction of anaesthesia and continued until the morning of the first postoperative day. Endothelin-1 (ET-1), vasopressin, atrial natriuretic peptide (ANP), and catecholamine plasma levels were measured from arterial blood samples. Measurements were carried out after induction of anaesthesia, 2 h after onset of surgery, at the end of surgery, 2 h after surgery, and on the morning of the first postoperative day. Results: Cardiac index (CI) increased significantly in the dopexamine group (from 2.61±0.41 to 4.57±0.78 1 · min^?1 · m^?2) and remained elevated until the morning of the first postoperative day. Oxygen delivery index (DO₂I) and oxygen consumption index (VO₂I) were also significantly increased in the dopexamine group (DO₂I: from 416±91 to 717±110 ml/m² · m²; VO₂I: from 98±25 to 157±22 ml/m² · m²), being significantly higher than in the control group. pHi remained stable only in the dopexamine patients, indicating adequate splanchnic perfusion. Vasopressive regulators of circulation increased significantly only in the untreated control patients (vasopressin: from 4.37±1.1 to 35.9±12.1 pg/ml; ET-1: from 2.88±0.91 to 6.91±1.20 pg/ml). Conclusion: Patients undergoing major abdominal surgery may profit from prophylactic perioperative administration of dopexamine hydrochloride in the form of improved haemodynamics and oxygenation as well as beneficial influence on important regulators of organ blood flow.     

A comparison of the inhibitory effects of four volatile anaesthetics on the metabolism of chlorzoxazone, a substrate for CYP2E1, in rabbits

Background: Halothane inhibits in vitro and in vivo activity of cytochrome P-450 (CYP) 2E1. There are several fluorinated volatile anaesthetics besides halothane, and most of them are defluorinated by CYP2E1. It is unclear whether other fluorinated anaesthetics inhibit the in vivo activity of CYP2E1.
Methods: We compared the inhibitory effects of therapeutic concentrations of four inhalational anaesthetics, halothane, enflurane, isoflurane, and sevoflurane, on chlorzoxazone metabolism in rabbits receiving artificial ventilation.
Results: All four inhalational anaesthetics decreased arterial blood pressure and increased plasma chlorzoxazone concentration. However, no significant differences in the plasma chlorzoxazone concentration were found between the four anaesthetics. The estimated chlorzoxazone clearance increased after beginning inhalation with all four agents, but no significant difference in clearance was noted between agents.
Conclusions: At therapeutic concentrations, the in vivo inhibitory effect on chlorzoxazone metabolism was similar for all four inhalational anaesthetics examined, even though their chemical characteristics and extent of hepatic metabolism differ considerably.     

Systemic analgesia adapted to the children's condition

A concept of balanced analgesia using nonsteroidal anti-inflammatory drugs (NSAIDs), paracetamol (acetaminophen), opioids, and corticosteroids can also be used in patients with pre-existing illnesses. NSAIDs are the most effective treatment for acute pain of moderate intensity in children; however, these drugs should be avoided in patients at increased risk for serious side effects, e.g. patients with renal impairment, bleeding tendency, or extreme prematurity. NSAIDs can be given with minimal risks to the younger child with mild to moderate asthma, and, in these patients, the use of steroids can be encouraged; in addition to their antiemetic and analgesic action, a beneficial effect on asthma symptoms can be expected. In the non-intubated child with cerebral trauma, exaggerated sedation caused by opioids and increased bleeding tendency caused by NSAIDs must be avoided. In neonates and small infants, the oral administration of sucrose or glucose is helpful to minimize pain reaction during short uncomfortable interventions.