贝伐单抗对裸鼠胃癌移植瘤血管内皮细胞生长因子和核转录因子Sp1表达的影响

目的 观察贝伐单抗对裸鼠胃癌移植瘤生长以及对肿瘤血管内皮细胞生长因子（VEGF）和核转录因子Sp1表达的影响.方法 建立SGC-7901胃癌细胞株裸鼠移植瘤模型,成瘤后分别使用贝伐单抗（BVZ组）和磷酸盐缓冲液（PBS组）治疗4周.绘制肿瘤生长曲线,免疫组织化学染色技术（IHC）检测移植瘤Ki-67、CD34、VEGF及Sp1表达情况,TUNEL法检测肿瘤细胞凋亡.结果 相比PBS组,BVZ组肿瘤生长速度明显减缓（P〈0.05）,肿瘤细胞增殖能力下降,凋亡指数明显增加[（5.3±1.8）％比（16.7±6.7）％,P＜0.01],肿瘤组织内微血管密度下降（4.0±1.0比16.3±1.5,P＜0.001）.贝伐单抗能减少肿瘤内VEGF表达,但对核转录因子Sp1表达水平没有明显影响.结论 贝伐单抗可有效抑制裸鼠胃癌移植瘤生长,减少肿瘤内微血管密度和VEGF表达,但不引起Sp1表达的明显改变.     

TP、HIF-1α、VEGF在乳腺癌中的表达及与血管生成关系的研究

目的:探讨TP、HIF-1α、VEGF在乳腺癌中的表达及其与血管生成关系.方法:免疫组化法检测15例正常乳腺组织标本和37例浸润性乳腺癌组织中HIF-1α、VEGF、TP的表达情况,同时以CD34为标记检测微血管密度(MVD).结果:乳腺癌组织中TP、HIF-1α、VEGF均存在高表达,与正常乳腺组织相比,差异具有显著性.TP、HIF-1α、VEGF表达阳性组的MVD值明显高于表达阴性组(P＜0.01).HIF-1α表达与VEGF呈正相关(rs＝0.357,P＜0.05),且HIF-1α阳性组TP表达明显高于阴性组(t﹦9.778,P＜0.01),随HIF-1α与VEGF表达的增加,TP逐渐增高.TP、HIF-1α、VEGF表达与乳腺癌有无淋巴结转移及组织学分级均呈正相关.结论:TP、HIF-1α、VEGF在乳腺癌组织存在高表达,并与肿瘤血管生成有关.     

Angiostatin基因联合反义HIF-1α基因治疗人肝癌裸鼠移植瘤的实验研究

目的研究Angiostatin基因联合反义缺氧诱导因子-1α(HIF-1α)基因治疗人肝癌裸鼠皮下移植瘤的协同抑制作用。方法用人肝癌细胞株SMMC-7721建立人肝癌裸鼠皮下移植瘤动物模型。四组荷瘤裸鼠分别注射质粒PcDNA3、Angiostatin/PcDNA3、HIF-1α/PcDNA3B、Angiostatin/ PcDNA3 HIF-1α/PcDNA3B。观察肿瘤生长曲线,检测肿瘤的Angiostatin、血管内皮生长因子(VEGF)、HIF-1α表达和微血管密度(MVD),利用TUNEL染色法行原位细胞凋亡分析。结果Angiostatin基因治疗在早期具有抑制肿瘤生长的作用;Angiostatin基因治疗组的MVD(24.8±2.8)低于空质粒对照组(30.2±4.1),VEGF表达高于空质粒对照组,细胞凋亡指数(2.87±0.48)高于空质粒对照组(1.55±0.43);联合治疗组有明显抑制肿瘤生长的作用,HIF-1α局部低表达,MVD (14.6±2.1)低于Angiostatin基因治疗组(24.8±2.8),VEGF表达低于单独治疗组,细胞凋亡指数(5.12±0.63)高于单独治疗组。结论肿瘤对Angiostatin基因治疗可以产生耐受性;反义HIF-1α基因阻断肿瘤的缺氧适应途径在一定程度上解决了抗血管生成治疗的耐药性问题。     

超声微泡联合Ad-EGFP/HIF-1α介导EPCs移植治疗大鼠心肌梗死

目的探讨超声微泡联合Ad-EGFP/HIF-1α介导内皮祖细胞（EPCs）移植治疗大鼠心肌梗死的可行性。方法将Ad-EGFP/HIF-1α转染EPCs。将30只SD大鼠建立心肌梗死模型后随机分为5组：空白对照组（C组）、超声＋微泡组（US＋MB组）、单纯EPCs组、超声＋EPCs组（US＋EPCs组）及超声＋微泡＋EPCs组（US＋MB＋EPCs组）。EPCs移植后4周,用超声心动图检测大鼠左心室收缩功能,免疫组织化学（I HC）染色法检测CD34的表达及微血管密度（MVD）,Western blot检测VEGF蛋白的表达。结果 US＋MB＋EPCs组射血分数、短轴缩短率高于其他各组（P〈0.05）,MVD计数高于其他各组（P〈0.05）且VEGF蛋白表达水平最高（P〈0.05）。结论超声微泡联合Ad-EGFP/HIF-1α介导EPCs移植可通过促进VEGF的高效表达、刺激心肌梗死周边区血管生成等途径改善心肌梗死大鼠的心功能。     

紫杉醇联合曲妥珠单抗对人乳腺癌SKBR-3细胞移植裸鼠的治疗作用

目的:观察紫杉醇联合曲妥珠单抗对人乳腺癌SKBR-3细胞移植裸鼠的治疗效果以及对瘤组织局部凋亡诱导因子程序性细胞死亡蛋白5(PDCD5)与凋亡抑制因子X-连锁凋亡抑制蛋白(XIAP)表达的影响。方法:用高表达Her-2的人乳腺癌SKBR-3细胞制备裸鼠皮下移植瘤模型,成瘤后,将荷瘤小鼠随机分组分别给予紫杉醇联合曲妥珠单抗(联合治疗组)、紫杉醇单药(紫杉醇组)、曲妥珠单抗单药(曲妥珠单抗组)、生理盐水(对照组)治疗。每周用药1次,6次后处死小鼠,取移植瘤称重后,分别用qPCR与Western bolt检测瘤组织PDCD5和XIAP基因与表达。结果:与对照组比较,各治疗组移植瘤质量均明显减小,瘤组织PDCD5mRNA与蛋白表达量均明显升高,XIAPmRNA与蛋白表达量均明显降低,且联合治疗组以上变化较2个单药组更为明显(均P0.05)。单药组间比较,紫杉醇组降低XIAPmRNA与蛋白表达的作用强于曲妥珠单抗单组(均P0.05),其他指标无统计学差异(均P0.05)。结论:紫杉醇联合曲妥珠单抗化疗能有效抑制Her-2阳性乳腺癌移植瘤在裸鼠体内的生长,其作用可能与促进肿瘤PDCD5表达、同时降低XIAP表达有关。     

反义HIF-1α基因治疗人肝癌裸鼠移植瘤的实验研究

摘要：目的:探讨反义HIF-1α基因对人肝癌裸鼠皮下移植瘤的影响及其相关机制。方法:使用人原发性肝癌细胞株SMMC-7721建立人肝癌裸鼠皮下移植瘤动物模型。待肿瘤生长至直径约0.4cm时，将荷瘤裸鼠随机分为3组，分别注射生理盐水、质粒PcDNA3和HIF-1α/PcDNA3B，质粒用脂质体DOTAP介导转染细胞。观察各组动物的肿瘤生长曲线；取肿瘤标本作免疫组织化学检查（SABC法）及蛋白质印迹检查，检测各组肿瘤的VEGF和HIF-1α表达及微血管密度（MVD）和细胞凋亡。结果:HIF-1α/PcDNA3B治疗组各时点的肿瘤体积，以及肿瘤组织中HIF-1α蛋白、MVD，VEGF表达均低于对照组，而细胞凋亡指数高于对照组，差异均有显著性（P＜0.05）。结论:通过阻断癌细胞的缺氧适应途径，反义HIF-1α基因治疗肝癌有抑制肿瘤生长、抑制肿瘤血管生成及诱导细胞凋亡的作用。     

外泌体微小RNA-let-7c靶向结合AGO1调控多发性骨髓瘤血管生成

目的探究多发性骨髓瘤外泌体中微小RNA(miR)-let-7c对血管内皮细胞生物学功能的影响及机制。方法从多发性骨髓瘤初治患者的骨髓活检标本中原代培养出骨髓瘤内皮细胞, 慢病毒感染后建立miR-let-7c过表达或抑制内皮细胞稳染株, 使用细胞计数试剂盒(CCK-8)、Transwell迁移实验及小管形成实验检测感染后内皮细胞的生物学行为改变, 并采用生物学信息技术预测miR-let-7c与argonaute1(AGO1)蛋白的靶向调控区, 双荧光素酶报告基因实验论证两者之间的靶向调控作用。构建多发性骨髓瘤移植瘤小鼠模型, 采用实时定量聚合酶链式反应(qRT-PCR)检测各组移植瘤组织中miR-let-7c的表达水平, 免疫组织化学标记内皮细胞表面CD31来计算各组肿瘤微血管密度(MVD);采用蛋白印迹法检测各组移植瘤组织中缺氧诱导因子1α (HIF-1α)、AGO1及血管内皮生长因子(VEGF)的蛋白表达;采用qRT-PCR检测各组移植瘤组织中HIF-1α、AGO1及VEGF的mRNA表达。两组均数间用独立样本t检验, 两组以上均数的比较用方差分析。结果用CCK-8试剂盒检测发现, ...     

线粒体融合素-2对裸鼠成瘤性及增殖、转移的影响

目的 观察线粒体融合素(mfn)-2对裸鼠成瘸性及增殖瘤的增殖、转移的影响.方法 裸鼠共分为3组:实验组、空载体对照组、空白对照组,分别将3组MCF-7细胞异种移植到无胸腺小鼠体内.建立裸鼠人乳腺癌移植瘤模型,比较3组裸鼠之间肿瘤的大小和重量,逆转录-聚合酶链反应(RT-PCR)检测3组肿瘤组织mfn2的表达,免疫组织化学半定量检测核增殖抗原(Ki-67)、血管内皮生长因子(VEGF)的表达.结果 实验组、空载体对照组、空白对照组3组肿瘤瘤体质量(单位:g)分别为1.78±0.13、2.84±0.16、2.77±0.12,实验组裸鼠肿瘤重量明显低于对照组(P<0.05),实验组瘤体的体积与两对照组比较差异有统计学意义(P<0.05),实验组mfn2基因高表达(P<0.05),两对照组低表达,两对照组之间差异无统计学意义(P>0.05),实验组与两对照组比较,实验组Ki-67的表达升高,而VEGF的表达明显降低(P<0.05).结论 mfn2基因可明显抑制人乳腺癌成瘤,对人乳腺癌裸鼠移植成瘤后的增殖和转移能力有影响.     

贝伐单抗在乳腺癌治疗中的应用

血管增殖在乳腺癌的进展和转移过程中起重要作用。贝伐单抗(bevacizumab)可以特异性阻断VEGF与其受体结合从而抑制肿瘤血管增殖。但目前对于贝伐单抗适应证的更新存在分歧。对于转移性乳腺癌的治疗加用贝伐单抗可以提高无进展生存率(PFS)和客观反应率(ORR),但未证实有总生存率(OS)的显著提高。笔者现就贝伐单抗在乳腺癌治疗的应用研究作一综述。     

TAMs/MCF-7细胞共培养体系VEGF过表达对裸鼠移植瘤Bcl-2表达的影响

目的 :探讨肿瘤相关巨噬细胞(TAMs)/MCF-7细胞共培养体系中VEGF过表达对裸鼠移植瘤Bcl-2表达的影响。方法:应用PMA及IL-4体外诱导活化TAMs细胞;Transwell非接触式共培养TAMs和MCF-7细胞;MCF-7细胞分为对照组、VEGF组和共培养细胞上清组,分别建立乳腺癌裸鼠移植瘤模型,计算促瘤率;Western blot法检测移植瘤中Bcl-2表达情况。结果:VEGF组和共培养细胞上清组平均瘤重较对照组均明显增加(P0.01),促瘤率分别为61.57%和66.61%。Bcl-2蛋白在VEGF组和共培养细胞上清组移植瘤组织中均呈高表达,且明显高于对照组(P0.01)。结论:乳腺癌细胞可过分泌VEGF等趋化因子,招募并活化TAMs,通过VEGF/Bcl-2旁分泌环路作用,抑制肿瘤细胞的凋亡,促进肿瘤进展。     

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.