眼镜蛇毒细胞毒素-12联合射线对裸鼠移植瘤的作用

目的探讨中华眼镜蛇毒细胞毒素-12(CTX-12)联合射线处理,对Balb/c裸鼠皮下移植膀胱肿瘤的生长抑制作用。方法建立40只Balb/c雌性裸鼠皮下移植瘤的动物模型,待肿瘤体积达到(0.60±0.09)cm3时,随机将动物按处理方法的不同分成CTX-12+放射组、单纯CTX-12组、单纯放射组和空白对照组,观察并比较各组的抑瘤率,并以流式细胞术、TUNEL系统检测肿瘤细胞凋亡情况。结果单纯放射组、单纯CTX-12组、CTX-12+放射组的抑瘤率分别为18.2%、46.7%、77.9%;与对照组比较,三组动物的皮下移植肿瘤都受到抑制(P<0.05);但CTX-12+放射组肿瘤受抑制程度明显高于单纯CTX-12组(P<0.05)和单纯放疗组(P<0.01);肿瘤细胞凋亡率及凋亡指数亦然。结论 CTX-12联合射线处理能显著抑制Balb/c裸小鼠皮下移植膀胱肿瘤的生长。CTX-12联合生理剂量射线主要是通过诱导肿瘤细胞凋亡而达到明显抗膀胱肿瘤作用。     

西黄丸及其主要成分抑制PI3K/Akt/mTOR信号通路促进PC-3荷瘤小鼠前列腺癌细胞的凋亡

目的:评估西黄丸及其主要成分对裸鼠去势抵抗性人前列腺癌PC-3细胞皮下移植瘤的PI3K/AKT/mTOR信号通路及细胞凋亡的影响.方法:通过西黄丸、麝香、牛黄、多西他赛、麝香+牛黄干预动物模型,计算各组抑瘤率及HE染色观察肿瘤细胞形态,采用qPCR方法检测各组PI3K/Akt/mTOR mRNA水平,Western印迹...     

转录因子E2F-1对裸鼠人胃癌细胞移植瘤生长的影响

目的 观察含有转录因子E2F-1的重组逆转录病毒载体(pLXSN-E2F-1)对裸鼠人胃癌细胞移植瘤E2F-1基因的表达和肿瘤生长的影响.方法 建立人胃癌MCC-803细胞裸鼠移植肿瘤模型,随机分为pLXSN-E2F-1组、pLXSN组、生理盐水组.隔天向各组分别注射相应药物0.2 ml,共7次,同时测量各组肿瘤体积.15 d后处死裸鼠,显微镜下观察移植瘤组织形态变化,用免疫组织化学法、半定量逆转录-聚合酶链反应(RT-PCR)和Western blot技术检测移植瘤中E2F-1基因的表达,脱氧核苷酸末端转移酶介导的缺口末端标记法(TUNEL)检测肿瘤细胞凋亡指数.结果 与生理盐水组和pLXSN组比较.pLXSN-E2F-1组肿瘤生长速度明显减慢(P<0.05);病理学观察确认所取组织为恶性肿瘤组织;免疫组织化学结果 显示pLXSN-E2F-1组的肿瘤细胞细胞质内有较多棕褐色颗粒沉着,pLXSN组和生理盐水组肿瘤细胞细胞质内均未见或偶见棕褐色颗粒沉着;半定量RT-PCR和Western blot结果 均显示pLXSN-E2F-1组E2F-1表达较pLXSN组和生理盐水组明显上调(P<0.05);pLXSN-E2F-1组的凋亡指数(15.4±4.1)%,显著高于pLXSN组(8.3±2.2)%和生理盐水组(8.1±2.3)%(P<0.05).结论 逆转录病毒载体pLXSN-E2F-1瘤内注射可抑制人胃癌裸鼠移植瘤的生长.     

脂质体生存素反义寡核苷酸抑制胃癌裸鼠皮下移植瘤生长的作用

目的探讨脂质体生存素反义寡核苷酸(ASODN)对人胃癌裸鼠皮下移植瘤生长的抑制作用及机理。方法将24只裸鼠建立人胃癌细胞系HS-746T皮下移植瘤模型,用不同的转染液处理后随机分成6组：空白对照组,脂质体组,正义链组,100、200和400nmol／L反义链组(ASODN组)。于注射相应试剂后2,4,8,12,16,20d观测裸鼠移植瘤体积,计算抑瘤率和肿瘤缩小率,观察移植瘤细胞形态变化,免疫组化SP法检测生存素的表达,并用逆转录聚合酶链反应技术(RT—PCR)和Western blot蛋白免疫印迹法比较治疗后不同时间各组肿瘤组织中生存素mRNA和蛋白表达的变化。结果注射后20d空白组、脂质体组和正义链组裸鼠的抑瘤率无明显差异,而ASODN组移植瘤的体积随着时间和浓度的增加而减小,肿瘤缩小率则增大,抑瘤率均大于对照组,400nmol／LASODN组抑瘤率最大为93％。光镜下见ASODN组移植瘤凋亡细胞数增多,生存素表达减弱,6例(6／12)肿瘤组织有坏死液化灶。各ASODN组均能够下调移植瘤细胞生存素mRNA含量,抑制生存素蛋白表达,注射20d后400nmol／L ASODN组蛋白表达为空白对照组的36．8％。结论生存素基因反义寡核苷酸能够通过诱导人胃癌裸鼠皮下移植瘤细胞凋亡,下调生存素mRNA和蛋白的表达,抑制裸鼠皮下移植瘤的生长。     

IL-6通过激活HIF-1α促进人胃癌MKN45细胞裸鼠移植瘤顺铂耐药的作用及机制研究

目的探讨IL-6介导的HIF-1α激活对人胃癌MKN45细胞裸鼠移植瘤顺铂耐药的影响。方法通过接种人胃癌MKN45细胞建立人胃癌裸鼠移植瘤模型。将胃癌移植瘤裸鼠分为三组:对照组,顺铂组和顺铂+IL-6组,每组10只。给药4周后,取出瘤体测量瘤重及抑瘤率,并用Western-blot法检测肿瘤组织中相关蛋白的表达。结果在瘤重方面,对照组顺铂+IL-6组顺铂组;在抑瘤率方面,顺铂组顺铂+IL-6组,差异有统计学意义(P0.05)。进一步研究发现IL-6诱导裸鼠移植瘤耐药主要通过激活HIF-1α,抑制下游凋亡通路(Bax,Bcl-2, Cleaved Caspase-9及Cleaved Caspase-3)的激活及诱导下游药物外排通路(P-gp和MRP1)的表达(P0.05)。结论 IL-6干预可促进人胃癌MKN45细胞裸鼠移植瘤顺铂耐药,其机制主要通过激活HIF-1α及下游信号通路。     

蟾毒灵对裸鼠结肠癌原位移植瘤凋亡基因Caspase-3表达的影响

目的:探讨蟾毒灵治疗裸鼠结肠癌原位移植瘤的作用及机制。方法 :应用不同剂量蟾毒灵(0.5、1.0、1.5 mg/kg)处理人结肠癌细胞株HCT-116建立的裸鼠原位移植瘤模型,分别用生理盐水(NS)(0.2 mL/只)、5-FU(25 mg/kg)做阴性(NS组)和阳性对照(5-FU组),测量移植瘤的体积,观察蟾毒灵对移植瘤的肿瘤抑制率、裸鼠生存期的影响;HE染色观察移植瘤的坏死程度;TUNEL标记法检测肿瘤细胞的凋亡指数;荧光定量PCR方法检测基因Caspase-3 mRNA的表达,免疫组化法和Western印迹法检测Caspase-3蛋白的表达。结果:蟾毒灵各剂量组和5-FU组裸鼠原位移植瘤体积明显小于NS组(P<0.05);蟾毒灵各组移植瘤的凋亡指数与NS组相比明显增加(P<0.05)。结论:蟾毒灵能够抑制裸鼠人结肠癌原位移植瘤的生长,促进肿瘤细胞凋亡,其机制可能与上调基因Caspase-3表达有关。     

阻断Wnt-1信号通路对裸鼠非小细胞肺癌的模型研究

目的通过建立宣威地区非小细胞肺癌的裸鼠移植瘤模型,探讨阻断Wnt-1信号传导通路对非小细胞肺癌的抑制作用。方法将21只重量16~18 g的荷瘤小鼠分为三组:空白组(n=7)、对照组(n=7)和实验组(n=7)。空白组注入生理盐水,对照组注入多西他赛,实验组注入Wnt-1抗体。待6次注射干预后,处死所有裸鼠获取肿瘤标本,比较其体积大小,比较空白组、对照组及实验组对肿瘤的抑瘤率。结果肿瘤体积在第21天和27天时空白组分别与实验组、对照组的差异有统计学意义(P=0.002,P=0.000)。体内实验结果显示,多西他赛和Wnt-1抗体对非小细胞肺癌均有抑制作用,多西他赛的抑制作用更强。结论阻断Wnt信号通路对肿瘤的生长有抑制作用,多西他赛和Wnt-1抗体对非小细胞肺癌的抑制有积极的效果。     

损伤调节自噬调控基因对胃癌SGC7901细胞裸鼠移植瘤放射敏感性的影响

目的研究损伤调节自噬调控基因（DRAM）对胃癌SGC7901细胞移植瘤放射敏感性的影响。方法取对数生长期的人胃癌SGC7901细胞建立裸鼠皮下移植瘤模型．随机分为空白对照组、DRAM组（在瘤体约为1．0cm^3时．在瘤周注射携带DRAM基因的腺病毒Admax-pDC315．DRAM—EGFP）、放疗组、放疗联合DRAM组。对瘤体进行剂量为10Gy局部放疗．分别在放疗后3、6、9d处死裸鼠,切取肿瘤,计算抑瘤率。用免疫组化方法检测P53、PCNA、C-myc、Fas—L蛋白的表达。结果放疗联合DRAM组的抑瘤率在3、6、9d分别为9．3％、14．1％、16．7％,均显著高于单纯放疗组（5．0％、8．8％、6．5％）（P〈0．05）;在空白对照组、DRAM组、放疗组、放疗联合DRAM组中．随时间延长PCNA和C-myc蛋白表达的阳性率逐渐下降．而P53和Fas—L蛋白表达的阳性率逐渐增强。结论DRAM基因可通过促进细胞凋亡和抑制细胞增殖．增强裸鼠皮下胃癌移植瘤的放射敏感性。     

5-氨基乙酰丙酸介导的光动力学对裸鼠人胃癌移植瘤的治疗作用

目的观察5-氨基乙酰丙酸（5-ALA）介导的光动力学治疗对裸鼠人胃癌移植瘤的治疗作用。探索5-ALA介导的光动力学（PDT）治疗胃癌的可能机制。方法以MGC-803人胃癌细胞制备裸鼠人胃癌移植瘤模型：整体荧光成像系统下观察动物瘤体发出的荧光信号：测量荷瘤对照组、单纯激光组、单纯5-ALA组和5-ALA介导的PDT治疗组治疗后第1、3、7、14、21天的裸鼠肿瘤大小并计算肿瘤体积：末次测量后切除肿瘤行病理检查和透射电镜观察，TUNEL法检测组织细胞凋亡。结果常规方法培养MGC一803人胃癌细胞并接种裸鼠．可以成功制备出裸鼠人胃癌移植瘤的模型：荷瘤裸鼠肿瘤组织在特定波长的荧光激发下可发出特有的红色荧光。荷瘤对照组、单纯激光组、单纯5-ALA组和5-ALA介导的PDT治疗组治疗后第1、3、7、14、21天4组间的肿瘤体积差异有统计学意义（肚1003．086，P=0．000），PDT治疗组明显小于其他3组；病理检查提示．PDT治疗后肿瘤细胞大片凝固性坏死；透射电镜观察提示，PDT治疗组肿瘤组织存在大量死亡细胞及部分凋亡细胞：TUNEL法检测发现，PDT治疗组的肿瘤组织凋亡指数显著高于其他3组（χ^2=18．237．P=0．000）。结论5-ALA介导的PDT对于裸鼠人胃癌移植瘤具有明显的治疗效果．而单纯给予5-ALA或激光辐射对肿瘤无明显抑制作用；肿瘤细胞的坏死及凋亡是5-ALA介导的PDT产生细胞毒作用的重要机制。     

新疆地区多中心阿比特龙和多西他赛治疗转移性去势抵抗性前列腺癌的临床疗效和安全性的对比分析

目的分析和比较新疆地区醋酸阿比特龙联合泼尼松+雄激素剥夺治疗(ADT)和多西他赛联合泼尼松+雄激素剥夺治疗(ADT)治疗转移性去势抵抗性前列腺癌(mCRPC)的临床疗效和安全性。方法回顾性分析新疆地区7家医院泌尿外科2016年6月至2018年1月收治的mCRPC患者的临床资料。阿比特龙组患者46名,多西他赛组患者48名,观察比较两组临床疗效和安全性的差异。结果中位随访时间15个月。中位影像学无进展生存期(rPFS)阿比特龙组和多西他赛组分别为15个月和11个月,中位前列腺特异性抗原无进展生存期(PSAPFS)阿比特龙组和多西他赛组分别为13个月和9个月。PSA反应率阿比特龙组63.04%,多西他赛组41.67%。在安全性方面,3～5级不良反应的比例阿比特龙组45.65%,多西他赛组47.92%。结论醋酸阿比特龙联合泼尼松+ADT治疗mCRPC相对于多西他赛联合泼尼松+ADT,改善患者rPFS、PSAPFS,提高PSA反应率。在不良反应方面,两种治疗方案无明显差异。     

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 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.     

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.     

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.     

Is the recovery profile of mivacurium independent of the rate of decay of its plasma concentration in patients with normal plasma cholinesterase activity?

Background: The duration of action of muscle relaxants is poorly correlated to the rate of decay of their plasma concentration. The plasma concentration of mivacurium may rapidly decrease below its active concentration because of the extensive hydrolysis of mivacurium. By inflating a tourniquet on one upper limb for 3 min after the administration of atracurium, mivacurium or vecuronium, we studied the influence of the initial decline of their plasma concentration on their effect. Methods: In 50 patients anaesthetised with thiopental, isoflurane and fentanyl, the effect of bolus doses of 0.15 or 0.25 mg . kg^?1 mivacurium (MIV 15, MIV 25), 0.3 or 0.5 mg . kg^?1 atracurium (ATR 30, ATR 50) and 0.06 or 0.1 mg . kg^?1 vecuronium (VEC 06, VEC 10) were measured on both arms (evoked response of the adductor pollicis to train-of-four stimulation every 12 s), a tourniquet being applied on one arm just before and during 3 min after the muscle relaxant bolus. Results: Tourniquet inflation of 3 min almost abolished the neuromuscular effect of mivacurium. In the vecuronium groups and in the ATR 50 group, tourniquet inflation did not modify the maximum degree of depression of the twitch response. Also, the duration of action of vecuronium was unaffected by the tourniquet. In the ATR 30 group, times to return of the twitch response to 25% (duration 25%) and 75% (duration 75%) of control response were significantly shorter in the cuffed arm, 23 min vs 27 min, and 41 min vs 45 min, respectively. In the ATR 50 group, only duration 25% was significantly shorter in the cuffed arm (41 min vs 45 min). Conclusion: The results suggest that the rate of decline of the plasma concentration of mivacurium is so rapid, that a very low and almost clinically ineffective concentration is present as soon as 3 min after its administration. The results also indicate that the recovery from a mivacurium-induced neuromuscular blockade is not influenced by the rate of decay of its plasma concentration in patients with genotypically normal plasma cholinesterase.     

Membranes in Artificial Organs

Abstract: Membrane processes play a pivotal and enabling role in modern replacement therapy for acute and chronic organ failure and in the management of immunologic diseases. In fact, virtually all contemporary extracorporeal blood purification methods employ membrane devices, and the next generation of artificial organs and tissue engineering therapies are almost certain to be similarly grounded in membrane technology. In this short essay, we comment on the similarities and differences among synthetic membranes and their natural counterparts and also provide a critical overview of the demographics and technology of hemodialysis, hemofiltration, apheresis, oxygenation, and emerging membrane technologies and applications.     

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.