光氧化处理脱细胞牛心包构建组织工程心肌补片的实验研究

目的 探讨经染料介导光氧化处理的脱细胞牛心包构建组织工程心肌补片的可行性。方法 新鲜牛心包先脱细胞,再经光氧化法处理,消毒后种植雄性SD骨髓间充质干细胞(MSCs)。结扎雌性大鼠左冠状动脉前降支,制作心肌梗死模型,1周后将符合心肌梗死标准的大鼠随机分成3组,心肌梗死对照组(MI)、补片组(P)、种细胞补片组(P+C)分别进行干预。4周后,超声评价心功能;2周、4周取材行组织学和免疫组化检查。结果 脱细胞处理完全去除了牛心包组织中的细胞,光氧化处理使组织结构致密;种植的细胞在组织表面形成连续的细胞层。P+C组牛心包心肌补片降解程度、微血管密度在2周、4周时均较P组大。超声评价补片4周后大鼠心功能,P+C组左室射血分数(LVEF)、左室缩短分数(LVFS)均较MI组和P组大,与MI组的差异有统计学意义。结论 光氧化处理脱细胞牛心包构建的组织工程心肌补片可以延缓心功能恶化,该处理方法具有良好的应用潜力。     

脱细胞牛心包构建引导骨再生膜的初步研究

目的制备具有良好生物相容性和适宜降解吸收时间的引导骨组织再生（guided bone regeneration，GBR）膜材料。方法采用0．25％Trypsin＋0．5％Triton X-100酶联脱细胞法对新鲜牛心包进行脱细胞处理，将脱细胞牛心包（A组）、甘油保存脱细胞牛心包（B组）、碳化二亚胺[1-ethyl-3-（3-dimethylamino propyl）carbodiimide hydrochloride，EDAC]交联脱细胞牛心包（C组）、甘油保存EDAC交联脱细胞牛心包（D组）4种膜材料分别植入38只SD大鼠背部皮下，不植人材料为E组。于2、4、8和16周分别处死大鼠7、12、12和7只，观察周围组织反应及材料的降解吸收情况。结果4种材料植入动物体内均有不同程度的炎性反应和纤维囊膜形成。术后4周，A组和C组的炎性反应轻微，纤维包膜变薄。A组膜材料吸收替代时间为8周左右，C组吸收替代时间为16周左右；16周时B组和D组材料仍有纤维包膜。结论EDAC交联脱细胞牛心包具有良好的生物相容性和理想的降解性能，在动物体内能顺利被自体组织替代。     

脱细胞牛心包种植人血管混合细胞构建组织工程心脏瓣膜

目的 探讨在脱细胞牛心包上种植人血管混合细胞构建组织工程心脏瓣膜的方法与效果.方法 将体外培养的人血管混合细胞种植在脱细胞牛心包材料上,观察种子细胞形态学和免疫组织化学变化和牛心包超微结构变化,并测定内皮细胞分泌t-PA和PAI-1的活性.结果 种子细胞全层覆盖脱细胞牛心包表面,并浸润至组织内部生长;牛心包表面为扁平、片状、分层的细胞覆盖,细胞表面有少量绒毛和纤细的纤维结构.免疫组化显示内皮细胞Ⅷ因子、平滑肌细胞α-肌动蛋白、成纤细胞Fibronectin相关抗原呈阳性表达;种子细胞能分泌纤溶活性物质t-PA和PAI-1.结论 人血管混合细胞种植后附着满意,与脱细胞牛心包生物相容性好,生长状况好,并具有内皮功能.     

脱细胞猪肺动脉带瓣管道的支架材料研究

目的研究心血管组织在经过适当脱细胞处理后的组织结构和生物学特性。方法对带瓣猪肺动脉管道进行脱细胞处理，所得组织和作为对照的新鲜天然组织分别进行HE染色、ETVG染色、免疫组化染色及扫描电镜检查，并测定各种大分子物质的含量；在小鼠皮下移植6周后测定组织钙含量及钙定位染色。结果脱细胞后的组织内未见细胞结构，基质结构基本保持。胶原和弹性蛋白含量增加。脱细胞后的组织在小鼠皮下移植后钙含量较天然组织明显下降。结论经过合适的脱细胞处理后，可以去除几乎所有的细胞成分，基本保留的基质结构，能显著减轻在异种移植时引起的钙化。     

脱细胞牛心包补片移植修复义眼台暴露的临床疗效分析

目的:探讨脱细胞牛心包补片移植修复义眼台暴露的临床效果。方法:对12例羟基磷灰石义眼台植入术后发生暴露的患者进行修复。将脱细胞牛心包补片覆盖于表面,修复缺损区,术后随访观察6~24月。结果:术后未出现结膜裂开及义眼台暴露,义眼活动良好。结论:脱细胞牛心包补片移植是修复义眼台暴露的有效方法。避免了应用异体组织修补排异反应的发生,对治疗该并发症具有一定的临床意义。     

骨髓间充质干细胞双向诱导分化构建血管化组织工程骨的实验研究

目的:探讨利用骨髓间充质干细胞(marrow stromal cells,MSCs)的成骨和成血管化特性双向诱导分化,构建血管化组织工程骨的新策略。方法:将体外培养扩增的MSCs,用含成骨诱导剂的培养液连续培养2周,形成成骨性细胞膜片。同时将另一部分MSCs向成血管化分化,获得血管内皮前体细胞(endothelial progenitor cells,EPCs),并将EPCs悬液接种于膜片,形成膜片-EPCs复合体。然后将膜片-EPCs复合体植入裸鼠体内,同时单纯植入MSCs膜片作为对照组。术后4周和8周取材,通过Micro-CT、组织学和扫描电镜检查,分析其成骨性能。结果:体外构建的细胞膜片为细胞-细胞外基质聚合体,细胞外基质中沉积有钙化结节。培养获得的EPCs能够形成管腔状结构,CD31染色表达阳性;膜片-EPCs复合体植入裸鼠体内4周和8周后,形成密布血管网的组织工程骨,成骨面积和血管密度均明显高于对照组。结论:掺入血管内皮前体细胞不仅有利于产生丰富血管网,而且能够促进新骨形成。     

生物材料补片修补大鼠左心室室壁瘤的实验研究

目的建立大鼠左心室室壁瘤补片模型，比较生物可降解材料p（3HB-co-3HH）／PU（PHB）与脱细胞牛心包片在该模型上的表现。方法取SD大鼠，结扎左冠状动脉，制成心梗模型。心梗模型制作6周后，行超声心动图检查，筛选合格模型大鼠，随机分成3组，PHB组（9只），脱细胞牛心包片组（9只），对照组（6只），前两组分别行左心室室壁瘤补片术，对照组仅行开胸手术。术后8周再次行超声心动图检查，并取补片做病理学检查。结果PHB组与脱细胞牛心包片组较对照组心功能明显改善（P〈0．01），但两组之间差异无统计学意义。大体病理显示两种补片局部均无室壁瘤形成，补片组织相容性好，心室面为内皮细胞覆盖。结论大鼠左心室室壁瘤补片模型可以满足进一步组织工程学心肌补片研究的需要，PHB补片与脱细胞牛心包片经过改进后可作为组织工程学心肌的支架材料。     

羟基铬减缓生物瓣钙化的实验研究：Ⅲ.羟基铬改性牛心包…

观察羟基铬改性牛心包瓣片以血管架桥的方式植入犬循环系，在与血液直接接触并在一定压力的情况下的抗钙化作用。经植入４个月后的组织试片形态学观察和原子吸收法组织钙含量测定，结果发现ＨＣ改性的组织瓣片在犬循环系植入４个月的模型中仍具有较好的抗钙化作用。     

猪脱细胞真皮基质修复兔腹壁缺损的实验研究

目的研究猪脱细胞真皮基质修复兔腹壁缺损的效果,探讨异种脱细胞真皮基质应用的可行性。方法健康小白猪1头,取背部及两侧皮肤制备脱细胞真皮基质。26只日本大耳白兔,雌雄不限,体重2.2～2.3 kg,随机分为对照组(n=6)和实验组(n=20)。对照组制备5.0 cm×0.5 cm腹壁缺损,单纯缝合关闭缺损。实验组制备5.0 cm×2.5 cm腹壁缺损,用同样大小的猪脱细胞真皮基质补片(简称"补片")修复,补片基底膜面朝向肠管。术后观察是否有疝形成,比较两组腹腔内脏器粘连情况,以及对照组腹壁肌筋膜单纯缝合处和实验组补片-腹壁肌筋膜吻合处的最大张力,组织学观察补片是否有纤维血管组织长入及其在体内的生物学转归。结果实验动物均无疝形成。术后5周,实验组补片和腹壁融为一体,补片皮肤面和脏器面均有纤维血管组织长入,补片处于新生组织掺入重建过程。实验组1只动物补片和腹腔内脏器粘连较重(2级),5只发生了轻微粘连(1级),12只无粘连(0级);对照组1只轻微粘连(1级),5只无粘连(0级);两组粘连分级比较差异无统计学意义(Z=—0.798,P=0.425)。术后5周,实验组补片-腹壁肌筋膜吻合处的最大张力为(13.0±5.5)N,对照组腹壁肌筋膜单纯缝合处为(13.6±4.0)N,差异无统计学意义(t=—0.410,P=0.683)。组织学观察显示,术后5周,实验组补片中有大量小血管,并有中性粒细胞及淋巴细胞为主的炎性浸润,补片边缘偶见巨噬细胞,补片-腹壁肌筋膜吻合处由纤维结缔组织连接;术后6个月,补片及周围炎性反应消退,胶原纤维结构发生了改建,补片和肌筋膜层由有纤维结缔组织愈合。结论补片修复兔腹壁缺损取得了较好效果,补片-腹壁肌筋膜层愈合,其吻合处的力学强度达到了自体腹壁单纯缝合吻合的力学强度,补片胶原纤维结构发生了改建。     

骨髓来源细胞构建组织工程血管补片

目的探讨组织工程方法构建血管补片的可行性。方法用壳聚糖和透明质酸多孔多聚体支架构建高分子复合材料支架，将犬的骨髓细胞种植其中，并植入自身犬的肺动脉上，观察材料上细胞外基质生成及表面内皮化的情况，分别在术后2周、4周、8周用电镜、组化等方法来进行评价。结果所有动物在实验期问均存活，组织学及免疫组织化学显示，术后补片形成类似血管壁样组织。结论此复合材料和骨髓细胞可用来构建组织工程血管补片，其结构与血管壁类似。     

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.     

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.     

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.     

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.