TrkB影响结肠癌细胞SW620侵袭能力及与ERK信号通路活化关系的研究

目的:探讨干扰结肠癌细胞TrkB蛋白表达及抑制ERK活化对细胞增殖、凋亡和侵袭以及细胞内ERK磷酸化水平的影响。方法:应用特异性TrkB-siRNA瞬时转染及ERK特异性抑制剂处理SW620结肠癌细胞,观察SW620细胞增殖、凋亡和侵袭情况以及细胞内ERK磷酸化水平的变化。结果:特异性siRNA转染高表达TrkB的SW620细胞,TrkB蛋白表达减少,ERK的磷酸化水平降低,且转染组细胞数显著低于对照组(P=0.001),转染组的细胞凋亡率显著高于对照组(P=0.000 1),24 h后侵袭至下层小室的细胞数转染组显著低于对照组(P=0.001);ERK抑制剂明显降低SW620细胞ERK磷酸化水平(P=0.001),而对ERK蛋白表达没有影响,且应用ERK抑制剂作用SW620细胞,对照组和处理组中细胞数没有显著差异(P=0.544),对照组和处理组中SW620细胞的凋亡率差异无统计学意义(P=0.103),但对照组24 h后侵袭至下层小室的细胞数显著高于处理组(P=0.0001)。结论:干扰TrkB蛋白表达能够降低高转移结肠腺癌SW620细胞内ERK磷酸化水平,促进细胞凋亡并抑制细胞增殖和侵袭。同时应用ERK特异性抑制剂也显著抑制细胞侵袭。因此ERK信号转导通路可能与TrkB介导的结肠腺癌细胞抗凋亡和侵袭能力的增加相关,沉默TrkB表达可能成为阻断结肠癌转移的新靶点。     

通过抑制ERK1/2通路诱导肝癌细胞SMMC-7721凋亡的研究

目的应用细胞外信号调节激酶(ERK)1/2抑制剂U0126研究ERK1/2在肝癌细胞增殖、凋亡中的作用。方法以肝癌SMMC-7721细胞株为材料,分为空白对照组及不同浓度的U0126处理组。以MTT检测细胞增殖情况,流式细胞仪分析细胞周期及细胞凋亡情况。结果不同浓度的U0126处理后均可明显抑制肝癌SMMC-7721细胞的增殖(P<0.05,P<0.01),使处于G0/G1期的细胞明显增多(P<0.05)且呈剂量依赖性,并诱发细胞凋亡发生(P<0.05)。结论阻断ERK1/2通路有可能成为肝癌治疗的重要手段。     

microRNA125a-3p对滋养层细胞功能的调控作用及机制

目的 观察microRNA125a-3p(miR-125a-3p)在滋养层细胞中的表达,探讨其对滋养层细胞增殖、侵袭和凋亡的调控及机制。方法 荧光实时定量PCR检测人滋养层细胞系HTR-8/SVneo、绒癌细胞系JAR和JEG-3中miR-125a-3p的表达情况。以HTR-8/SVneo和JEG-3细胞为实验对象,分为3组：空白对照组(CK组),未做任何处理;阴性对照组(NC组),转染NC-inhibitor;实验组(inhibitor组),转染miR-125a-3p inhibitor。以Transwell、流式细胞仪、CCK8法分别检测细胞的侵袭、凋亡及增殖能力。Western blot检测Fyn蛋白表达情况及ERK1/2、STAT3磷酸化水平。荧光实时定量PCR检测Fyn mRNA水平,免疫共沉淀法检测Fyn活性水平。结果 miR-125a-3p mRNA表达水平在HTR-8/SVneo、JAR和JEG-3细胞中依次降低,两两比较均有统计学差异(P<0.01)。抑制HTR-8/SVneo和JEG-3中miR-125a-3p后,细胞的凋亡水平明显降低,侵袭和增殖能力均明显升...     

STAT3抑制剂对人原发性肝癌细胞生长的影响

目的 观察STAT3抑制剂对人原发性肝癌细胞增殖的抑制和诱导细胞凋亡.方法 对照组为人原发性肝癌细胞株(HepG2、Huh7),实验组为对照组+STAT3抑制剂(Piceatannol),阴性对照组为人宫颈癌细胞株(Hela),阳性对照组为Hela细胞+干扰素(IFN)-α.Western blot测定STAT3蛋白和磷酸化STAT3蛋白在人肝癌细胞中的表达水平,流式细胞仪检测细胞周期和细胞凋亡率.结果 (1)STAT3蛋白和磷酸化STAT3蛋白构成性表达于人肝癌细胞HepG2和Huh7.STAT3抑制剂抑制实验组磷酸化STAT3蛋白的表达.(2)实验组HepG2的S期细胞的比例[24 h,(15.48±4.91)%～(40.24±0.96)%,P<0.05;48 h,(19.16±1.70)%～(25.62±1.41)%,P<0.05]和Huh7的S期细胞的比例[24 h,(8.55±0.69)%～(31.62±0.20)%,P<0.05;48 h,(7.57±0.62)%～(30.88 ±0.04)%,P<0.05]明显低于对照组;实验组HepG2细胞的早期细胞凋亡率明显高于对照组[(4.50±0.76)%～(2.58±0.76)%,P<0.05],实验组Huh7细胞的早期细胞凋亡率[24 h,(8.27±2.47)%～(23.95±4.72)%,P<0.05]和晚期细胞凋亡率[24 h,(11.6±2.39)%～(25.27±3.51)%,P<0.01;48 h,(11.27±0.87)%～(33.9±2.4)%,P<0.05]明显高于对照组.结论 STAT3抑制剂可以通过阻断JAK-STAT3信号通路途径抑制人原发性肝癌细胞的增殖和诱导凋亡.     

bFGF和TGF-β1对原代培养的前列腺间质细胞的作用

目的:探讨碱性成纤维细胞生长因子(bFGF)和转化生长因子β1(TGF-β1)在良性前列腺增生(BPH)中的作用。方法:培养了人BPH间质细胞,采用MTT法检测无血清培养的间质细胞的增殖,用免疫组化方法检测平滑肌细胞表型变化,观察不同浓度bFGF和TGF-β1对培养的人BPH间质细胞的影响。结果:bFGF促进间质细胞增殖(P<0.05、P<0.01),较高浓度时(10μg/L)降低平滑肌细胞表型表达;TGF-β1(>0.1μg/L)抑制间质细胞增殖并增加平滑肌细胞表型表达(P<0.05、P<0.01);5μg/L的bFGF与0.001μg/L和0.01μg/L TGF-β1作用间质细胞,促进细胞增殖(P<0.01),与0.1μg/L,1μg/L及10μg/L TGF-β1作用间质细胞,抑制细胞增殖,0.1μg/L时对细胞的抑制作用轻微(P>0.05),1μg/L及10μg/L时出现明显的抑制(P<0.01),同时TGF-β1在较高浓度时(>1μg/L),平滑肌细胞表型表达明显增加(P<0.01)。结论:bFGF以时间和浓度依赖的方式促进培养的增生前列腺间质细胞的增殖,并减少平滑肌细胞表型表达;TGF-β1抑制间质细胞的生长并诱导间质细胞向平滑肌细胞分化,两者共同在BPH的形成机制中发挥着重要作用。     

移植静脉肌-内皮连接偶联系统早期重建对平滑肌细胞转化态的影响及意义

目的探讨肌-内皮连接偶联系统在移植静脉重塑早期对血管平滑肌细胞(VSMC)表型转化态的影响。方法20只大鼠随机分为实验组(基因转染组)与对照组(非基因转染组),于术后14d取出移植静脉,采用反转录多聚酶链反应(RT-PCR)及电镜等检测并观察缺氧诱导因子-1α(HIF-α)表达水平、肌-内皮连接结构、血管内皮细胞(VEC)及血管平滑肌细胞(VSMC)表型。结果实验组较对照组HIF-Iα过表达,VEC增生显著,VSMC以收缩表型居多,肌-内皮连接结构重建显著(P均<0.01)。结论肌-内皮连接偶联系统是稳定移植静脉重塑早期VSMC转化态重要的组织结构和评估血管结构与功能良好重建的重要标志物之一。     

细胞外信号调节激酶1/2及c-fos在门静脉高压症患者脾静脉壁的表达及意义

目的探讨丝裂原激活蛋白激酶(MAPK)信号传导通路是否参与门静脉高压性血管病变的发生过程.方法实验组为乙肝后肝硬化门静脉高压症患者18例,住院期间行择期脾切除加贲门周围血管离断术.对照组选取同期因外伤性脾破裂急诊入院行脾切除术患者10例.采用Western blot方法检测脾静脉组织总蛋白中磷酸化细胞外信号调节激酶丝裂原ERK1/2的表达.采用免疫组织化学方法观察c-fos在脾静脉组织中的表达情况.结果实验组脾静脉壁ERK1/2活性较正常组明显增高(P<0.01).实验组脾静脉壁c-fos表达增高,平均染色指数为6.267 5±0.312 4,正常组脾静脉壁c-fos表达增高,平均染色指数为1.821 3±0.504 1,两者比较差异有统计学意义(P<0.01).c-fos在平滑肌细胞中强阳性表达.结论 ERK1/2/c-fos信号传导途径与门静脉高压性血管病变的发生有关,ERK1/2/c-fos信号传导途径可能是血管平滑肌细胞表型转变的重要调控途径.     

可卡因诱导不同年龄段大鼠生殖系统损害模型的建立及生精细胞凋亡状况的研究

目的 建立可卡因诱导不同年龄段大鼠生殖系统损害动物模型,探讨可卡因对不同年龄段大鼠生精细胞凋亡影响。方法 应用3、6、12周龄SD雄性大鼠皮下注射可卡因28d建立吸毒动物模型。测定血清性激素浓度,分析生殖细胞凋亡状况。结果 可卡因诱导4周后,3周龄大鼠睾丸重量减轻(P<0.05),其他生殖器官重量无明显影响;6周龄大鼠睾丸、附睾和阴茎重量减轻(P<0.05),其中睾丸重量差异有非常显著性(P<0.01);12周龄大鼠生殖器官重量则均无明显影响(P>0.05)。3周龄实验组大鼠睾酮(T)降低,雌二醇(E2)升高(P<0.05);6周龄实验组大鼠T明显降低(P<0.05),而E2变化;12周龄实验组大鼠T、E2差异无显著性(P>0.05)。3个年龄段实验组大鼠均出现细胞凋亡梯带,生精细胞凋亡峰值明显增高,其中6周龄组最为显著。3、6和12周龄实验组大鼠睾丸生精细胞半胱天冬蛋白酶-3(Caspase-3)活性均较对照组明显增高,其中6周龄实验组 Caspase-3活性增高更为明显(P<0.01),Caspase-3活性增加与血清雄激素水平呈负相关(P<0.05)。结论 可卡因诱导不同年龄段大鼠 28 d可致大鼠生殖器官发育和生殖内分泌功能损害,造成生精细胞凋亡增加,增殖能力下降。该模型是研究毒品影响不同年龄段雄性大鼠生殖系统损害较为理想的方法。     

吡格列酮对静脉旁路血管内膜增生的影响

目的 探讨吡格列酮(PIO)对静脉旁路血管内膜增生的影响及可能机制.方法 将32只SD大鼠随机分为2组,分别予(3mg·kg-1·d-1)的PIO或盐水灌胃,1周后行自体右颈外静脉-颈总动脉移植术,术后持续给药2、4周后取静脉旁路血管.应用图像分析软件计算内膜增厚情况,westernbolt检测ERK1/2激活情况.体外培养人大隐静脉平滑肌细胞,采用CCK-8法检测细胞增殖,TUNEL法检测细胞凋亡.结果 与同期对照组相比,PIO明显减少术后2周[(8.56±1.64)μm对(25.44±0.89) μm,P＜0.01]和4周[(10.51 ±1.47) μm对(35.69±1.07) μm,P＜0.01]静脉旁路血管内膜厚度,抑制ERK1/2活性.PIO显著抑制PDGF-BB诱导的细胞增殖并促进细胞凋亡.结论 PIO能有效抑制静脉旁路血管术后内膜增生,可能与其下调ERK1/2活性,抑制血管平滑肌细胞增殖并促进凋亡密切相关.     

阴茎海绵体平滑肌细胞表型转化及其影响因子的研究进展

阴茎海绵体平滑肌细胞是组成阴茎海绵体的主要功能成分,其表型转化是平滑肌细胞增殖和迁移的关键性起始步骤。因此,探讨平滑肌细胞表型转化的机制及其影响因子在阴茎勃起功能障碍的防治过程中具有重要意义。目前通常将平滑肌细胞分为收缩型(分化型)和合成型(未分化型、增殖型或去分化型)两种类型,并发现L转化生长因子(TGF-β)、转录因子E2F1、基本转录元件结合蛋白2(BTEB2)、胰岛素等因素可能影响平滑肌细胞表型转化。本文就近年来阴茎海绵体平滑肌细胞表型转化及其影响因子的研究进展作一简要综述。     

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.     

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.     

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.     

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.     

Intraoperative autotransfusion is associated with modest reduction of allogeneic transfusion in prosthetic hip surgery

Background: The efficacy of intraoperative salvage and washing of wound blood and the predictors of allogeneic red cell transfusions in prosthetic hip surgery are insufficiently known.
Methods: In 96 patients, undergoing primary or revision surgery, salvaged and washed red cells and, if necessary, allogeneic blood were used to keep haematocrit not lower than 33%. The bleeding of red cells during hospital stay was calculated from the red cell balance. The preoperative red cell reserve (millilitres of red cells in excess of a haematocrit of 33%) was estimated and the difference between this volume and the total bleeding of red cells was retrospectively used to classify patients with regard to the need for red cells. Stepwise regression analysis was used to define patient-related variables associated with allogeneic blood transfusion.
Results: Preoperative knowledge of the type of operation (primary, revision), the preoperative red cell reserve, and the body mass could predict roughly half of the need for banked blood (r²=0.45). Only one-third of the total bleeding of red cells was retransfused. For complete avoidance of allogeneic blood, autotransfusion was most effective in patients with a moderate need (0–4 u). However, 32% of such patients required allogeneic blood.
Conclusions: Autotransfusion has a limited efficacy to decrease the need for allogeneic blood, and other blood-saving methods should be added for this purpose. It is difficult to predict the need for allogeneic blood preoperatively.     

缺氧对肾小管上皮细胞分泌外泌体的影响

目的    观察缺氧对肾小管上皮细胞分泌外泌体的影响,探讨外泌体在缺氧致肾脏损伤中的作用及机制。 方法    （1）常氧（21% O₂）及缺氧（1% O₂）分别处理大鼠肾小管上皮细胞（NRK-52E）48 h,收集细胞上清液并使用高速梯度离心法分离外泌体。采用透射电镜、纳米示踪分析、Western印迹、蛋白浓度定量鉴定并比较两组外泌体的基本特性。（2）在共培养实验中,以不同浓度（1、10、50、100、300 mg/L）的常氧外泌体、缺氧外泌体分别干预脂多糖（LPS）诱导的大鼠原代腹腔巨噬细胞,使用实时荧光定量PCR与酶联免疫吸附试验（ELISA）法分别检测巨噬细胞白细胞介素6（IL-6）、肿瘤坏死因子α（TNF-α）、诱导型氮氧化物合酶（iNOS）水平;使用Western印迹法检测巨噬细胞磷酸化（p）STAT/STAT及细胞因子信号传导抑制蛋白1（SOCS1）的蛋白表达;最后,使用实时荧光定量PCR法检测常氧外泌体与缺氧外泌体中炎性反应相关微RNA（microRNA,miR）的表达差异。 结果    （1）离心得到的囊泡具有外泌体典型的结构,粒径小于150 nm,表达外泌体标志蛋白CD63,说明分离得到外泌体。缺氧对肾小管上皮细胞分泌的外泌体形态、粒径分布比例无明显影响,但提高了外泌体的分泌量。（2）缺氧外泌体相比于常氧外泌体促进了LPS诱导的M1型巨噬细胞IL-6、TNF-α、iNOS 的表达和分泌（均P＜0.01）,同时提高STAT的磷酸化水平并减少SOCS1的蛋白表达（均P＜0.01）;对炎性反应相关microRNA检测发现缺氧外泌体中miR-155、miR-27a表达量较常氧外泌体明显升高（P＜0.05）。 结论    缺氧可改变外泌体的生物学功能,表现为协同促进LPS诱导的M1型巨噬细胞的表型转化,这可能是慢性肾脏病微炎性反应状态持续的原因之一。     

In Vitro Function and Durability Assessment of a Novel Polyurethane Heart Valve Prosthesis

Abstract While flexible-leaflet, central-flow prosthetic heart valves promise relief from anticoagulation therapy, they continue to be restricted by inadequate durability. In consequence, a novel trileaflet valve, made entirely from polyurethane, has been developed. A batch of 6 consecutively manufactured polyurethane valves was subjected to hydrodynamic function and accelerated fatigue testing. Computerized data acquisition and control systems have been introduced to improve valve testing methodologies. In terms of hydrodynamic function, the polyurethane valve demonstrates transvalvular pressure gradients similar to those for a bioprosthetic valve (Carpentier-Edwards) and levels of retrograde flow significantly less than those for either the bioprosthetic valve or a bileaflet mechanical valve (St Jude Medical). The equivalent of 10 years of cycling without failure has been exceeded by all 6 polyurethane valves in accelerated fatigue tests with 2 valves remaining intact after 674 million cycles (equivalent to approximately 17 years) in continuing tests. Highspeed photography revealed considerable differences in leaflet motion between valves cycled at accelerated and physiological rates.     

Negative pressure ventilation vs. spontaneous assisted ventilation during rigid bronchoscopy: A controlled randomised trial

Background: Ventilation during interventional rigid bronchoscopy (IRB) under general anaesthesia (jet ventilation, positive pressure ventilation and spontaneous assisted ventilation) may offer some difficulties. This study compares the effectiveness during IRB of intermittent negative pressure ventilation (INPV) and spontaneous assisted ventilation (SAV). Methods: Thirty-eight patients submitted to IRB were randomised into two groups: SAV or INPV. All patients received a total intravenous anaesthesia; INPV patients were paralysed. Pre-and intra-operative arterial blood gases and O₂ flow through a rigid bronchoscope were assessed. The endoscopist applying a subjective score evaluated the operating conditions. Results: Patients of the INPV group, as compared to the SAV group, required a lower dosage of fentanyl (2.6 ± 1.8 (μg · kg^?1· h^?1 vs. 6.6 ± 4.8 μg · kg^?1· h^?1), a lower O₂ supply (3.3 ± 2.8 1/min vs. 11.6 ± 3.4 1/min), a shorter recovery time (5.4 ± 2.9 min vs. 9.8 ± 7.1 min) and no manually assisted ventilation (0 ± 0 vs. 1 ± 1.1 nd?/procedure). Intraoperative PaCO₂ was higher in the SAV (8.1 ± 1.3 kPa) than in the INPV group (5.0 ± 1.6 kPa) and intraoperative pH differed in the two groups (7.26 ± 0.05, SAV vs. 7.47 ± 0.08, INPV). Operating conditions, as assessed by a subjective score, were considered better with INPV than with SAV (4.9 vs. 4.3). Conclusions: As compared to SAV, INPV in paralysed patients during IRB reduces administration of opioids, shortens recovery time, prevents respiratory acidosis, excludes the need for manually assisted ventilation, reduces 02 need and affords optimal surgical conditions. INPV appears a safe, non-invasive and effective ventilatory management during IRB.