涂层双相陶瓷复合BMSC修复骨缺损的实验观察

目的比较双相陶瓷（Biphasie calcium phosphate，BCP）经低结晶羟基磷灰石（Low crystalline hydroxyapatite，LcHA）涂覆改性后构建的组织工程化骨（LcBCP）与单纯BCP复合骨髓基质干细胞（Bone marrow stromal cells，BMSCs）修复兔桡骨节段性缺损的成骨差异。方法BMSCs复合LcBCP（实验组）修复12只兔左侧桡骨15mm缺损；BMSCs复合BCP（对照组）植入右侧桡骨同样大小缺损，植入后第4、8和12周取材，通过大体形态、组织学、影像学和生物力学检测骨缺损修复效果。结果BMSCs—LcBCP复合物在体内骨缺损处生长良好。X线检测显示实验组连接处骨痂形成，对照组连接处在各个时间点愈合稍差。12周时，实验组骨修复良好，髓腔再通，组织学显示板层骨形成，连接处骨性愈合；对照组连接处尚有较多编织骨形成。实验组和对照组生物力学检测有统计学差异。结论BMSCs—LcBCP复合物可修复兔桡骨节段性缺损，低品态羟基磷灰石涂层有助于增强双相陶瓷的成骨能力。     

可降解复合人工骨修复骨缺损的实验研究

[目的]探讨硫酸钙（CS）／骨基质明胶（BMG）复合人工骨修复节段性骨缺损的能力。[方法]分别制备CS、BMG，按一定比例复合，植入兔尺骨15mm骨缺损，并随机分为3组，CS／BMG组植入复合人工骨、CS组单纯植入硫酸钙、空白对照组缺损区旷置。标本于术后4、8、12周分批取材，经大体观察、影像学、组织学及四环素荧光示踪检测，观察修复骨缺损的效果。[结果]术后切口均一期愈合，植入区周围未见炎性细胞浸润。CS／BMG组植入4周，缺损区两端及中央均可见岛状新骨生长，8周时材料已完全降解，新骨生长活跃，并逐渐由编织骨重塑为板层骨，12周缺损区被新生骨替代，骨结构逐渐成熟，与宿主骨间形成骨性桥接，髓腔再通，完成骨性修复。CS组4周两端也见新骨生长，但较CS／BMG组成骨量少，中央部位新骨出现时间晚。8周时材料完全降解吸收，植入区可见大量骨痂生长，两端出现板层样新骨，12周缺损区得到基本修复，但骨髓腔轮廓不清。空白组术后形成骨不连。[结论]。CS／BMG复合人工骨具有良好的生物相容性和可降解性，能有效地修复兔尺骨骨缺损，是一种较为理想的骨移植替代材料。     

微小颗粒骨磷酸钙复合物作为骨组织工程支架材料的实验研究

目的探讨使用同种异体微小颗粒骨磷酸钙骨水泥（CPC）复合物作为骨组织工程支架材料的方法。方法采用同种异体微小颗粒骨CPC复合物作为支架材料，将rh—BMP与CPC液相混合，再与兔骨膜成骨细胞及毛细血管内皮细胞复合培养，制成组织工程化人工骨。将人工骨移植到兔骶棘肌肌袋内，于术后4、8、12周进行Masson三色法组织学观察、扫描及透射电镜观察，观察其骨化及血管化情况。再将兔的桡骨制成骨缺损模型，用组织工程人工骨进行修复，于术后4、8、12周摄X线片检查、苏木精-伊红染色，观察骨缺损修复情况。结果肌袋内成骨实验，除4周时A组与B组的新骨形成面积百分比无显著性差异（P〉0．05）外，其余时间段两组的新生骨面积及新生血管面积相比具有显著性差异（P〈0．05）。修复骨缺损实验，A组新骨形成的速度、质量均明显优于B组。结论同种异体微小颗粒骨CPC复合物是一种良好的骨组织工程支架材料，有利于组织工程骨快速完成骨化及血管化。     

利用可生物降解共聚膜引导骨再生

目的　采用生物降解可吸收材料聚己内酯（ Ｐ Ｃ Ｌ）和聚乳酸（ Ｐ Ｌ Ａ）共聚膜修复长骨节段性骨缺损,探讨其引导性骨再生的效果及机制。方法　采用兔桡骨中段１２ ｃｍ 节段性骨缺损（保留骨膜）动物模型２４ 只,平均分成两组,实验组用膜包绕骨缺损区,对照组缺损区不处置,分别于术后３、６ 及１２ 周处死动物,进行 Ｘ 线片、大体及组织学观察。结果　实验组缺损区骨生长明显优于对照组,术后 ３ 周实验组可见明显的骨痂沿膜外生长;术后 ６ 周以桥接的外骨痂形成骨性连接;术后１２ 周膜内外均形成骨性连接,对照组从术后６ 周开始表现为骨不连。结论　利用可生物降解的膜性材料可引导骨组织再生,通过膜外骨痂以及形成相对迟缓的膜内骨痂共同完成骨缺损的修复;膜性材料通过屏障作用一方面有效地阻挡纤维组织长入缺损区,防止骨不连形成,另一方面在局部形成营养物质浓聚,并通过表面的微孔为骨细胞生长充当支架,促进骨缺损愈合。     

可控微结构电子束熔化成形钛合金支架作为成骨细胞载体修复兔骨缺损的研究

目的 探讨可控微结构电子束熔化成形钛合金支架作为成骨细胞载体修复兔骨缺损的可行性.方法 应用电子束熔化成形技术制备支架,将成骨细胞与支架复合培养7 d后,通过扫描电镜观察细胞与材料复合情况.将培养7 d的支架/细胞复合物及单纯支架植入兔体内.72只雄性新西兰白兔均制作骨膜-骨缺损模型后随机分为4组(n=18):A组缺损处植入细胞/支架复合物,B组缺损处植入单纯支架,C组缺损处旷置,D组缺损处置入自体骨.分别在第4、8、12周取材,行大体观察、四环素荧光标记、组织学观察以及新生骨定量分析等评价新骨形成及缺损愈合情况.结果 支架与细胞体外共培养7 d后,支架表面及内部孔隙有大量细胞黏附并与材料牢固结合.第12周,新生骨组织和血管不仅在支架周围有生长,而且沿着支架的管道结构向支架内部生长并逐渐填满支架内部,新生骨组织与支架牢固结合并形成一个相互嵌合的复合体.新生骨定量分析显示:第4周,各组间两两比较,差异均无统计学意义(P＞0.05).第8周,A组分别与B、C组比较,差异均有统计学意义(P＜0.05);D组分别与B、C组比较,差异均有统计学意义(P＜0.05).第12周,组间两两比较,差异均有统计学意义(P＜0.05).结论 可控微结构电子束熔化成形钛合金支架具有良好的生物相容性,能够促进支架内新骨生成及缺损的愈合.     

组织工程骨修复山羊胫骨节段性缺损的实验研究

目的应用自体骨髓基质干细胞（BMSCs）复合β-磷酸三钙（β-TCP）构建组织工程化骨，修复山羊胫骨节段性缺损。方法体外扩增培养、成骨诱导山羊BMSCs。实验组将第2代细胞复合β-TCP后修复山羊自体右侧胫骨26mm的节段性缺损（n=8），对照组以单纯β-TCP材料植入骨缺损处（n=8），旷置组（n=2）。术后16、32周分别通过大体形态观察、影像学、组织学和生物力学的方法检测骨缺损的修复效果。结果旷置组术后32周骨缺损未修复，表明动物模型确实可靠。大体观察、X线片和MicroCT显示16周时实验组已有新骨形成，β-TCP材料降解吸收；对照组则只形成少量骨痂，材料无明显降解。组织学检测示实验组有大量幼稚编织骨生成，对照组为纤维结缔组织，并有大量材料残余。实验组骨密度和力学强度低于正常胫骨组（P〈0．05），但明显高于对照组（P〈0．01）。术后32周时大体观察X线片和MicroCT显示术后实验组骨愈合良好，对照组为骨不连；骨密度检测示实验组明显高于对照组（P〈0．05），且与正常胫骨组差异无统计学意义（P〉0．05）。组织学检测示实验组呈骨性愈合，有较多成熟骨组织，对照组为纤维连接。生物力学测试实验组与正常胫骨力学强度差异无统计学意义（P〉0．05）。结论成骨诱导的自体BMSCs复合β-TCP形成的组织工程骨可良好修复山羊胫骨节段性缺损。     

关节－干骺端软骨细胞移植修复兔桡骨缺损

目的研究组织工程软骨移植于成年兔桡骨缺损后的生长、分化与转归特点,以及引导性骨再生和骨缺损的修复机制。方法取自一日龄新生兔关节－干骺端复合物的软骨细胞在几丁质纤维网中增殖21d后装入硅胶管内,套接在成年兔桡骨干1cm的缺损处（实验组12只）;对照组10只在缺损处套接空硅胶管,2只仅填入裸几丁质纤维。术后4周两组各处死3只动物取材,其余在术后16周取材。结果实验组术后4周3只动物的工程软骨组织在骨缺损内形成软骨样组织,术后16周9只动物中有2只动物的缺损愈合。对照组术后4周已开始骨愈合,术后16周9只动物的骨缺损全部愈合。结论新生兔关节－干骺端复合物的软骨细胞在成年兔桡骨缺损区（套管内）未肥大钙化,未再现软骨内化骨过程。缺损内的工程软骨可能因占据空间、阻碍成骨成分进入而中断了骨缺损修复过程。引导性骨再生的机制可能是人工膜管加强了骨膜的天然引导作用而促进了骨愈合。     

骨碎补/聚乳酸-羟基乙酸共聚物微囊复合自固化磷酸钙治疗家兔股骨缺损模型的实验研究

目的 探讨骨碎补/聚乳酸-羟基乙酸共聚物(DR-PLGA)微囊与自固化磷酸钙人工骨(CPC)复合物对家兔股骨骨缺损的影响.方法 将8只新西兰大白兔数字随机分为实验组(n=4)和对照组(n=4),制备家兔股骨骨缺损模型,分别植入DR-PLGA/CPC复合体与不含骨碎补的PLGA/CPC骨支架,分别于术后4周、8周通过X线、大体解剖、组织学观察评价其提高成骨活性、促进骨折愈合的效果.结果 术后4周、8周X线及组织学观察显示实验组促进骨愈合、提高成骨活性均优于对照组.结论 DR-PLGA/CPC复合体可诱导新生骨形成,促进骨愈合.     

以生物衍生材料为支架的组织工程骨移植早期兔外周血T淋巴细胞亚群的变化

目的检测体外构建的组织工程骨移植后兔外周血T细胞亚群的变化，对移植组织进行组织学观察，探讨以生物衍生材料作为骨组织工程支架材料的可行性。方法组织工程骨以兔骨膜来源的成骨细胞为种子细胞，经抗原自消化、部分脱钙、冻干后的异体骨为支架材料于体外构建。将健康新西兰白兔48只制成1cm长桡骨缺损模型后，随机分成A～D4组，每组12只，分别用部分脱钙冻干骨（partial demineralized freeze—dried bone，PDFDB）、组织工程骨、自体骨、同种异体骨植入兔桡骨节段性缺损。术后1、2、4周取材，用流式细胞仪检测4种材料移植早期兔外周血T淋巴细胞亚群的变化；通过常规组织学检测观察2、4、8、12周时4种材料的成骨作用。结果B组术后2周材料孔隙内有成骨细胞和成软骨细胞，可见骨、软骨混合性新生物形成，周边分布有破骨细胞，部分网架呈蚕食状被破坏吸收。术后4周，形成的新生骨过渡为编织骨。A、B组材料植入后1、2周外周血CD4^＋和CD8^＋T细胞较术前明显升高（P〈0．05）；术后4周CD4^＋T细胞较术前轻度偏高，但无统计学差异（P〉0．05）。C组术后CD4^＋和CD8^＋T细胞升高不明显（P〉0．05）。D组术后1、2、4周外周血CD4^＋和CD8^＋T细胞较术前及其他各组同期均明显增高（P〈.．05）。结论PDFDB为支架材料构建的细胞一材料复合物移植后外周血T淋巴细胞增高，但不影响其良好的修复骨缺损能力，生物衍生骨可作为支架材料应用于骨组织工程研究。     

胶原支架增强自固化磷酸钙骨水泥的力学及成骨性能研究

[目的]研究胶原支架（CS）对磷酸钙骨水泥（CPC）的力学及其在体内成骨的影响。[方法]试验分CPC／CS及CPC两组，三点弯曲试验测试材料的强度和弹性模量；组织学观察材料植入兔股骨22及54周的成骨状况。[结果]CPC／CS比CPC的弯曲强度、韧性强度分别提高了64．2％、3933．3％，弹性模量降低了45．7％；组织学显示22周CPC／CS内的胶原支架已完全被新骨替代，CPC只在边缘有少量成骨及材料降解而内部无成骨；54周CPC／CS已大部分降解孔化，孔内充满大量新骨及髓样组织，而CPC边缘区的成骨及材料降解虽比22周时明显，但其内部仍未见成骨。[结论]胶原支架既可改善CPC的力学性能，又能促进新骨长入CPC／CS复合材料内部，因此，CPC／胶原支架是较好的骨缺损修复材料。     

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.