消化道肿瘤凋亡抑制蛋白表达与体外化疗药物敏感性的关系

目的 探讨消化道肿瘤中p53、survivin、bcl-2蛋白表达与肿瘤细胞体外化疗药物敏感性的关系.方法 对84例胃癌和大肠癌进行MTT法体外化疗药物敏感实验和p53、survivin、bcl-2蛋白免疫组化染色,分析3种凋亡抑制蛋白与9种化疗药物对肿瘤细胞抑制的关系. 结果 本组肿瘤中p53、survivin、bcl-2蛋白表达率分别为64%、89%、61%,survivin与Bcl-2蛋白表达具有正相关性(r=0.3027,P＜0.05).p53强表达与紫杉醇、顺铂对肿瘤细胞抑制率明显降低有关(t=2.1282,P=0.0363;t=3.8850,P=0.0002);survivin蛋白强表达时,长春新碱、顺铂对肿瘤细胞的抑制率明显降低(t=2.1693,P=0.0329;t=2.0247,P=0.0046),但奥沙利铂对肿瘤细胞的抑制率明显增加(t=-2.9070,P=0.0047);bcl-2强表达时,氟尿嘧啶、长春新碱、表阿霉素、奥沙利铂对肿瘤细胞的抑制率明显低于弱表达组(t=2.1483～3.2330,P=0.0347～0.0018).结论 消化道肿瘤凋亡抑制蛋白的表达程度与部分化疗药物耐药性有关,评价某种耐药因子与肿瘤化疗药物敏感性的关系时必须考虑其他因素的影响.     

槐耳清膏体外逆转人乳腺癌细胞MCF-7耐三苯氧胺的研究

目的 探讨槐耳清膏体外逆转人乳腺癌细胞MCF-7耐三苯氧胺(TAM)的作用及其机制.方法 使用噻唑蓝(MTT)比色法测定不同药物处理对耐TAM的乳腺癌细胞株MCF-7/R的抑制率,流式细胞仪检测不同处理后MCF-7/R的凋亡情况和细胞周期变化.Western blot检测MCF-7/R不同处理后各组Phospho-P44/42MAPK(ERK1/2)及P44/42MAPK(ERK1/2)表达的差异.结果 MTT实验结果显示MCF-7/R的联合用药组抑制率(45.99±6.06)%和单药组抑制率(40.20±5.54)%分别与TAM对照组比较,差异有统计学意义(P＜0.05);流式细胞检测结果显示与TAM对照组比较,MCF-7/R的联合用药组和单药组G1期峰前出现显著的凋亡峰,且联合用药组的凋亡率(20.03%)与单药组的凋亡率(11.06%)与TAM对照组(2.15%)比较作用显著;Western blot检测蛋白表达经灰度分析显示,药物作用12 h后Phospho-P44/42MAPK(ERK1/2)蛋白在联合用药组的表达(0.3153±0.0179)和单药组的表达(0.5362±0.0030)分别与TAM对照组(0.9752±0.0034)比较均有下降,差异有统计学意义(P＜0.05),且联合组与单药组比较,差异有统计学意义(P＜0.05).结论 槐耳清膏具有体外逆转MCF-7/R细胞对TAM的耐药作用,逆转机制可能与下调MAPK通路磷酸化蛋白ERK1/2的表达水平相关,提示槐耳清膏是一种有意义的耐药逆转剂.     

葡萄籽多酚对人乳腺癌细胞MCF-7/ADR在裸鼠体内的多药耐药逆转作用

目的　研究葡萄籽多酚 (GSP)对人乳腺癌耐阿霉素细胞MCF 7/ADR的体内多药耐药逆转作用。方法　采用人乳腺癌裸鼠移植瘤模型研究GSP对肿瘤多药耐药的体内逆转作用 ;采用流式细胞术测定不同用药P 糖蛋白 (Pgp)表达变化及肿瘤细胞凋亡率变化。 结果　体内裸鼠抑瘤实验显示GSP有一定抑瘤作用 ,抑制率为 18 35 % ,联合应用阿霉素 (ADR)可显著抑制肿瘤生长 ,2 0mg/kgGSP可有效逆转MCF 7/ADR细胞的耐药性 ,抑瘤率为 5 4 6 4 %。流式细胞术结果显示应用GSP后肿瘤细胞Pgp表达显著降低 ( 32 0 3± 2 0 9) ,与对照组 ( 5 5 13± 2 12 )相比差异有显著意义 (P <0 0 5 )。平均凋亡率为 15 12 %± 1 0 4 % ,显著高于对照组 9 0 7%± 0 4 3% (P <0 0 5 )。结论　GSP能在体内逆转MCF 7/ADR细胞的耐药性 ,其机制可能是通过抑制Pgp表达 ,并可能通过诱导肿瘤细胞凋亡来起作用     

肿瘤坏死因子相关诱导凋亡配体联合化疗药物治疗膀胱癌的研究

目的　探讨肿瘤坏死因子相关诱导凋亡配体 (TRAIL)治疗膀胱肿瘤的作用 ,以及与化疗药物的协同作用。方法　将T2 4及 5 63 7膀胱肿瘤细胞接种至 96孔培养板后分别加入浓度为1、10、10 0 μg/L的TRAIL ,0 .1、1.0、10 .0mg/L的阿霉素 (ADM )和丝裂霉素 (MMC) ,不同浓度的TRAIL、ADM、TRAIL和MMC ,噻唑蓝比色 (MTT)法分别检测肿瘤细胞的生存率。将膀胱肿瘤细胞接种至 12孔板 ,培育 2 4h后加入不同浓度的TRAIL、ADM、MMC、TRAIL联合ADM、MMC。用流式细胞术检测不同处理组肿瘤细胞的凋亡率和死亡率。结果　 10 0 μg/LTRAIL引起T2 4、5 63 7细胞的凋亡率分别为 2 0 .1%、45 .3 % ,与无药物组 1.1%、3 .5 %的凋亡率比较差异有非常显著性(P <0 .0 1)。单独运用 10mg/LMMC、ADM对T2 4、5 63 7的抑制率分别为 3 6.0 %、44 .1%、2 6.7%、3 0 .2 % ;而 10 0 μg/LTRAIL和 10mg/LMMC、ADM联合后对T2 4、5 63 7的抑制率分别达到 5 8.4%、73 .7%、90 .7%、88.2 % ,两者有明显的协同作用 (P <0 .0 5 )。结论　在体外实验中 ,TRAIL可通过诱导肿瘤细胞的凋亡而产生抗膀胱肿瘤的作用 ;TRAIL与化疗药物ADM、MMC有协同抗肿瘤作用     

消化道肿瘤环氧合酶-2表达与凋亡抑制蛋白及化疗药敏性的关系

目的 探讨消化道肿瘤环氧合酶(COX)-2表达与凋亡抑制蛋白及体外化疗药敏性的关系.方法 对84例胃癌、大肠癌标本进行噻唑蓝(MTT)比色法体外化疗药物敏感性实验,并进行COX-2、p53、Survivin、bel-2免疫组织化学染色.结果 肿瘤组织COX-2、p53、Survivin、bel-2表达率分别为70.3%、64.3%、89.3%、60.7%;COX-2与Survivin、bcl-2表达呈正相关(r=0.5072、0.3783,均P<0.01).在肿瘤COX-2强表达组,紫杉醇(PTX)、表阿霉素(eADM)、羟基喜树碱(OPT)对肿瘤细胞抑制率明显低于弱表达组(均P<0.05);p53强表达与PTX、顺铂(DDP)对肿瘤细胞的抑制率明显降低有关(均P<0.05);Survivin强表达时,长春新碱(VCR)、DDP对肿瘤细胞抑制率明显降低(均P<0.05);bcl-2强表达时,5-氟尿嘧啶(5-Fu)、VCR、eADM、奥沙利铂(OXA)对肿瘤细胞抑制率明显低于弱表达组(均P<0.05).结论 消化道肿瘤COX-2通过抑制肿瘤细胞凋亡参与了肿瘤的多药耐药.     

消化道肿瘤转移淋巴结中P糖蛋白和谷胱甘肽S转移酶π的表达与肿瘤化疗药物敏感性的关系

目的 探讨消化道肿瘤淋巴结转移灶中P糖蛋白(P-gp)和谷胱甘肽S转移酶π(GST-π)的表达与化疗药物敏感性的关系及其临床意义.方法 对54例胃癌和大肠癌新鲜肿瘤组织及转移淋巴结进行肿瘤细胞培养化疗药敏性实验,行原发灶和转移灶P-gP和GST-π免疫组化染色.结果 ①肿瘤原发灶和淋巴结转移灶中P-gp和GST-π表达一致率较低,分别为22%(k=-0.0133,P=0.8698)和50%(k=0.1137,P=0.1496);淋巴结转移灶中P-gP和GST-π表达强度均明显高于原发灶(Z=-3.0448,P=0.0023;Z=-2.1178,P=0.0034).②VCR、OPT、OXA、DDP、MTX对淋巴结转移灶肿瘤细胞抑制率明显低于原发灶(均P<0.05),仅VP-16对原发灶的抑制率明显低于转移灶(P=0.0406).③原发灶中P-gp表达程度与5-FU、VCR和PTX对肿瘤细胞抑制率呈负相关(r=-0.4142～-0.5712,均P<0.05),GST-π表达程度与5-FU、VCR、OPT和PTX的抑制率呈负相关(r=-0.3927～-0.4951,均P<0.05);转移灶中P-gP表达程度与VP-16、PTX和eADM对肿瘤细胞抑制率呈负相关(r=-0.3802～-0.4624,均P<0.05),GST-π表达程度与5-FU、VCR、DDP的抑制率呈负相关(r=-0.3996～-0.5345,均P<0.05).结论 消化道肿瘤淋巴结转移灶中P-gP和GST-π的表达以及对化疗药物的敏感性均存在与原发灶不同的异质性,淋巴结转移灶具有更强的耐药倾向.术后辅助化疗的靶目标应针对淋巴结转移灶.     

聚集素在前列腺正常、增生、癌组织中的表达及意义

目的　通过检测聚集素 (Clusterin)在前列腺正常、增生、癌变组织中的表达 ,探讨其与前列腺疾病发生发展的关系。　方法　采用免疫组织化学染色法检测 12例正常前列腺组织、15例良性前列腺增生组织 (BPH)、5 6例前列腺癌标本中Clusterin的表达水平。　结果　 3种组织中Clusterin的阳性及弱阳性表达率为 81% (67/83 ) ,其中前列腺正常、增生、癌组织中阳性及弱阳性表达率分别为17% (2 /12 )、73 % (11/15 )、96% (5 4/5 6)。前列腺癌组织中Clusterin表达水平明显高于前列腺正常 (t=8 82 ,P <0 0 1)及增生 (t =7 63 ,P <0 0 1)组织 ,且在癌组织中与肿瘤病理分级 (r =0 64 9,P <0 0 1)、临床分期 (r=0 60 9,P <0 0 1)呈正相关。　结论　Clusterin可能通过抗凋亡机制在前列腺癌的生物特性中发挥着重要的作用     

胃癌凋亡相关蛋白Survivin、B淋巴细胞/白血病-2、bax表达与肿瘤细胞体外化疗药敏性的关系

目的 探讨胃癌凋亡相关蛋白表达与体外化疗药敏性的关系. 方法 对64例胃癌标本进行Survivin、R淋巴细胞/白血病-2(bcl-2)、bax免疫组织化学染色,并以噻唑蓝(MTT)比色法检测体外化疗药物敏感性.结果 肿瘤Survivin、bcl-2、bax阳性表达率分别为90.6％、75.0％、68.8％;Survivin与bax、bcl-2与bax 间表达强度均呈负相关(r=-0.45044、-0.414 03,P＜0.01).在耐药因子表达程度与药物对肿瘤细胞抑制率的关系中,Survivin强表达时,表阿霉素(eADM)、顺铂(DDP)对肿瘤细胞的抑制率明显降低(P＜0.05),但奥沙利铂(L-OHP)对肿瘤细胞的抑制率明显增加(P＜0.05);bcl-2强表达时,5-氟尿嘧啶(5-Fu)、紫杉醇(PTX)、eADM对肿瘤细胞的抑制率明显低于弱表达组(P＜0.05);bax强表达组中,5-Fu、eADM、L-OHP和甲氨喋呤(MTX)对肿瘤细胞的抑制率明显高于弱表达组(P＜0.05).结论 胃癌凋亡相关蛋白表达与部分化疗药物敏感性有关.     

奥曲肽诱导大鼠肝部分切除术后种植性肝癌细胞凋亡的研究

目的　以Wistar大鼠种植性肝癌模型为研究对象 ,探讨不同作用时间奥曲肽对肝部分切除术后肝癌细胞的凋亡变化。方法　 4 8只雄性Wistar大鼠行肝左叶切除加肝右叶肿瘤种植后 ,随机分为对照组 (n =16 ) ,奥曲肽治疗组 (n =16 ) ,奥曲肽延迟治疗组 (n =16 )。术后 1周、2周各取 8只处死 ,运用碘化丙啶 (PI)染色法和荧光素标记的膜联蛋白V(FITC AnnexinV)联合碘化丙啶 (PI)染色法检测肝癌细胞凋亡。结果　术后 1周和 2周时 ,治疗组肿瘤细胞的凋亡率明显高于对照组 ,差异有显著性 (P <0 0 1) ,所不同的是 1周时 ,治疗组的细胞凋亡率高于延迟治疗组 (P <0 0 1) ,而 2周时二者间则无差异 (P >0 0 5 )。结论　奥曲肽可以有效诱导大鼠种植性肝癌细胞的凋亡 ,并在早期呈现一定的时间效应     

靶向survivin的反义寡核苷酸联合三苯氧胺治疗乳腺癌的研究

目的研究联合应用靶向survivin的反义寡核苷酸(ASODN)和三苯氧胺(TAM)对MCF-7乳腺癌细胞的作用。方法将一条20mer的ASODN序列与TAM作用于MCF-7乳腺癌细胞,分别为TAM组(单独应用TAM)、ASODN组(单独应用ASODN)及TAM+ASOND联合组(联合应用TAM+ASODN).运用四甲基偶氮唑盐比色试验(MTT)、流式细胞仪(FCM)、原位杂交以及分光光度法分别检测各组MCF-7细胞的抑制率、细胞周期和凋亡率、survivin mRNA表达和caspase-3活性。结果 TAM+ASOND联合组对MCF-7细胞的抑制率〔(62.26±3.92)%〕明显高于TAM组〔(42.30±6.63)%〕及ASODN组〔(54.77±9.99)%〕,P0.05.TAM+ASOND联合组的细胞凋亡率为(28.08±4.32)%,明显高于TAM组〔(18.94±4.01)%〕及ASODN组〔(21.12±3.95)%〕,P0.01.TAM+ASODN联合组对MCF-7细胞的G0/G1期阻滞作用明显强于TAM组和ASODN组(P0.05,P0.01);TAM+ASODN联合组survivin mRNA表达阳性率为(13.38±3.45)%,明显低于TAM组〔(39.67±7.42)%〕或ASODN组〔(27.50±5.80)%〕,P0.01.TAM+ASOND联合组MCF-7细胞的caspase-3活性(0.93±0.13)高于TAM组(0.50±0.09)或ASODN组(0.64±0.08),P0.01.结论靶向survivin的反义寡核苷酸能够促进MCF-7乳腺癌细胞凋亡,增加其对TAM治疗的敏感性。     

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.     

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.     

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.     

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.     

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.     

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.