神经干细胞转染胶质细胞源性神经营养因子基因后的分化表现

目的观察转基因神经干细胞(NSC)体外外源基因的表达及转基因后的分化。方法体外转基因筛选得到稳定表达胶质细胞源性神经营养因子(GDNF)的脊髓源神经干细胞系(SP-NSC),通过流式分选(FACS),比较转基因前、后及血清对NSC分化为神经元及神经胶质细胞比例的变化;并采用Westernblot法检测传代后目的基因的表达。结果转基因后GDNF表达至少能稳定到转基因后6周;转基因后NSC分化为神经元的比例由转基因前(53.9±3.5)%提高到转基因后的(67.5±1.2)%,而血清组胶质细胞分化明显。结论SP-NSC转染GDNF后能稳定表达目的基因,转基因能显著增加后裔细胞中神经元比例,为转基因治疗中枢神经系统疾病研究奠定了基础。     

胶质细胞源性神经营养因子(GDNF)在大鼠骨髓基质干细胞中的表达

目的构建表达外源性胶质细胞源性神经营养因子(GDNF)的转基因大鼠骨髓基质干细胞(BMSCs),拟应用于脊髓损伤的基因治疗研究。方法提取新生大鼠肾组织mRNA,用逆转录PCR法扩增GDNF全长cDNA,构建其真核表达载体PEG-GFP-GDNF,酶切及测序鉴定;然后转染原代培养的大鼠BMSCs,荧光免疫细胞化学及细胞形态学检测GDNF的表达。结果扩增到全长687bp序列准确的GDNF编码片段,并在GDNF转基因原代大鼠BMSCs中检测到重组GDNF的表达。结论体外可构建成功表达GDNF的转基因BMSCs,有望应用于脊髓损伤等中枢神经系统疾病的治疗研究。     

超顺磁氧化铁、绿色荧光蛋白双标胶质细胞源性神经营养因子基因修饰中脑神经前体细胞的建立

目的 建立超顺磁氧化铁(SPIO)、绿色荧光蛋白(EGFP)双标胶质细胞源性神经营养因子(GDNF)基因修饰中脑神经干细胞.方法 以质粒pEGFPNl-GDNF转染大鼠胚胎中脑神经干细胞,SPIO标记细胞.荧光显微镜、免疫细胞化学和Western blot鉴定EGFP、GDNF表达;普鲁士蓝染色、透射电镜鉴定SPIO标记率;诱导分化后免疫细胞化学鉴定其分化能力.结果 基因转染12 h后EGFP开始表达;免疫细胞化学、Western blot表明GDNF能正确表达;普鲁士蓝染色示SPIO标记率达100%,透射电镜示SHO颗粒位于吞饮小泡和胞质内;体外诱导分化研究表明SPIO、EG-FP双标记不影响其分化.结论 成功建立SPIO、EGFP双标GDNF基因修饰中脑神经干细胞.     

胶质细胞源性神经营养因子体内转基因对皮质脊髓束再生的影响

目的通过非病毒载体阳离子脂质体介导,探讨胶质细胞源性神经营养因子(GDNF)基因体内转染对成年大鼠脊髓损伤后皮质脊髓束再生的影响.方法采用NystrOm法制备大鼠胸髓后路压迫损伤模型,压迫重量为50 g,时间为5 min,造成大鼠胸段脊髓急性重度损伤.用微量注射器将阳离子脂质体DC-Chol 6μl和重组质粒pEGFP-GDNF cDNA 2μg混合后注入大鼠损伤脊髓.应用逆转录-聚合酶链反应(RT-PCR)技术和荧光显微镜检测GDNF体内转基因后在局部的表达,通过辣根过氧化物酶(HRP)顺行追踪技术和神经微丝(NF)免疫组织化学活性的变化来评价GDNF基因体内转染对大鼠皮质脊髓束再生的影响.结果 GDNF基因体内转染1周后显示在基因注射局部有转录和蛋白水平表达.脊髓损伤后4周在损伤区可见较多的皮质脊髓束再生,损伤区NF阳性轴突数(524.33±80.55)/低倍视野较对照组(309.84±56.65)/低倍视野明显增多(P＜0.01).结论阳离子脂质体介导GDNF体内转基因能促进近端皮质脊髓束再生和神经骨架蛋白的修复.     

神经干细胞和施万细胞共移植治疗大鼠脊髓损伤

目的 观察神经干细胞和和施万细胞共移植治疗脊髓损伤的可行性。方法 体外培养胚胎脊髓源神经干细胞和施万细胞，将两种细胞共同移植到大鼠脊髓损伤部位，免疫组织化学染色鉴定神经干细胞在脊髓内的分化情况并观察记录大鼠行为学功能的恢复程度。结果 神经干细胞体外培养血清诱导分化可见大量具有少突胶质细胞特征的分化细胞，与施万细胞共培养则可促进神经干细胞向神经元方向分化。两种细胞共移植至脊髓损伤部位后，施万细胞可以促进神经干细胞的分化和成熟；共移植可以促进脊髓功能的恢复。结论 神经干细胞在体内和体外都具有多向分化能力，且其分化方向和成熟程度可以被多种环境因子所调控。神经干细胞和施万细胞共移植可以促进脊髓功能恢复。     

腺病毒介导的胶质细胞源性神经营养因子基因在体外骨髓基质干细胞中的表达及其生物学活性实验研究

本研究中我们将腺病毒介导的胶质细胞源性神经营养因子（Adv-GDNF）基因感染体外培养的骨髓问质干细胞（BMSCs），从基因转录水平检测GDNF在体外BMSCs中的表达。同时我们还将体外感染的BMSCs与脊髓背根神经节共同培养，间接观察了BMSCs表达的GDNF的生物学活性。     

胶质细胞源性神经营养因子和肿瘤坏死因子可溶性受体基因修饰的神经干细胞联合移植治疗脊髓损伤的实验研究

目的探讨胶质细胞源性神经营养因子（GDNF）和肿瘤坏死因子可溶性受体（sTNFR）腺病毒感染的人神经干细胞移植治疗脊髓损伤模型的可行性。方法先包装和扩增含GDNF和sTNFR基因的重组腺病毒，然后用该腺病毒感染人神经干细胞，再将这些神经干细胞移植到脊髓损伤局部。实验动物与分组：雄性sD大鼠，A组：hGDNF和sTNFR转基因神经干细胞移植组；B组：空病毒转基因神经干细胞移植组；c组：神经干细胞移植组；D组：只横断脊髓，不作移植；E组：对照组，只咬除棘突和椎板，不横断脊髓，不做其他处理；F组：不作任何处理。免疫组化检测外源基因的局部表达，最后进行组织学检查和BBB功能评分。结果免疫组化显示局部有外源基因表达，A组BBB功能评分优于C组，但组织学结果未见明显优势；这两组BBB评分显著优于阴性对照组，组织形态也有明显改善。结论腺病毒介导的GDNF和sTNFR基因修饰的神经干细胞移植是一种较好的脊髓损伤治疗方法。     

胶质细胞源性神经营养因子对哺乳动物精原干细胞增殖及分化的影响

胶质细胞源性神经营养因子(GDNF)是转化因子β(TGF-β)超家族的一个相关成员,在哺乳动物睾丸中由支持细胞分泌,对精原干细胞(SSCs)的增殖和分化具有非常重要的作用。体外培养SSCs时培养液中添加适量的GDNF能够促进SSCs的增殖。GDNF介导多种信号通路调节SSCs的自我更新和分化。本文就GDNF对哺乳动物精原干细胞增殖与分化的作用及其所介导的信号通路进行了综述。     

胶质细胞源性神经营养因子与脊髓损伤治疗

脊髓损伤治疗是医学界的热点和难点,从传统的大剂量激素冲击、手术解除压迫、术后康复锻炼等到干细胞移植、基因疗法等均未取得满意效果.大量研究证实,胶质细胞源性神经营养因子(GDNF)有促进脊髓损伤修复的作用,为脊髓损伤治疗带来新方法.该文就GDNF结构特性及在脊髓损伤修复中的作用研究进展作一综述.     

阳离子脂质体介导GDNF体内转基因对脊髓损伤后运动神经元的保护作用

目的 :观察阳离子脂质体介导的胶质细胞源性神经营养因子 (GDNF)体内转基因对大鼠脊髓损伤 (SCI)后伤区脊髓前角运动神经元的影响。方法 :采用改良Nystr m法制备大鼠胸段脊髓后路压迫损伤模型 ,将阳离子脂质体DC Chol和重组质粒 pEGFP GDNFcDNA混合后直接注入大鼠损伤脊髓。利用RT PCR技术和荧光显微镜检测GDNF体内转基因的表达。应用尼氏染色、酶组织化学染色方法观察前角运动神经元死亡的数目和胆碱酯酶(CHE)及酸性磷酸酶 (ACP)的变化。结果 :1周后在注射局部GDNFmRNA和GDNF有较高表达。GDNF体内转基因早期 (1～ 4周 )SCI区前角运动神经元死亡的数目减少 ,CHE和ACP变化的幅度降低。结论 :GDNF体内转基因能减少脊髓不完全性损伤后引起的神经元坏死 ,阳离子脂质体介导GDNF体内转基因治疗创伤性SCI的方法是可行的。     

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.