异常应力环境下兔颈椎软骨终板蛋白聚糖变化的实验研究

目的 :观察长时间异常应力环境下兔颈椎软骨终板蛋白聚糖 (PG )含量及组分的变化 ,探讨颈椎间盘退变的发生机制。方法 :将 2 8只家兔随机分为对照组和实验组 ,实验组家兔颈椎处于屈曲 45°(5h/次·d)异常应力环境下 ,分别于处理前及处理后 1、2、3个月处死动物 ,取C4～ 5和C5～ 6颈椎间盘软骨终板 ,作阿利新蓝染色和生化方法测定PG含量与组分比例 ,比较各组间可能存在的差异。结果 :对照组终板阿利新蓝染色和PG各组分的含量未发生显著变化 ,实验组阿利新蓝染色变浅 ,PG总量、硫酸软骨素 (CS)和硫酸角质素 (KS)比值、透明质酸 (HA)含量明显下降 (P <0 .0 5 ) ,并随着异常应力的作用时间延长而变化更为显著 (P <0 .0 1)。结论 :异常应力环境下颈椎软骨终板PG含量明显下降 ,并主要以CS下降为主 ,PG和CS的含量下降是终板退变和生物力学性能改变的原因之一。     

兔颈椎终板胶原结构变化对运动节段力学性能的影响

目的 通过测定兔退变颈椎运动节段力学参数的改变,观测其软骨终板胶原的超微结构变化,为退变的椎间盘显现异常力学特性作材料结构上的探讨。方法 将24只家兔随机分为对照组和模型组,模型组家兔保持45°低屈曲位5 h/d,取C5,6、C6,7进行生物力学测定,同时电镜观察终板胶原组织结构改变,总结分析终板材料的结构变化对运动节段力学性能的影响。结果 模型组终板抗扭强度、抗压强度、断裂时的最大形变都低于对照组,胶原排列从有序、致密、规整到紊乱、松散、溶解,并随造模进程的深入而加剧。结论 长时间的应力不均状态,造成椎间盘终板材料力学特性改变;终板胶原结构改变是颈椎间盘生物力学性能减退的原因之一。     

颈椎间盘压缩力学性能改变与终板蛋白多糖变化关系的实验研究

目的:探讨颈椎间盘退变时基质各成分的变化及其对椎间盘力学性能的影响。方法:将24只家兔随机分为对照组和模型组(n=12),模型组保持45°低屈曲位5h/次/d,最长持续3个月。分别于造模后1、2、3个月时各处死4只动物,取C5/6椎间盘测定终板糖胺多糖(glycosaminoglycan,GAG)总量、硫酸软骨素(chongdroitinsulphate,CS)与硫酸角质素(keratansulphate,KS)比值和透明质酸(hyaluronicacid,HA)含量;同时作力学测定。结果:模型组终板抗压强度、断裂时的最大形变、终板基质GAG总含量、CS/KS比值、HA含量都低于对照组(P<0.05),并随造模时间的延长两组差异越显著。结论:长时间的应力不均可造成椎间盘终板材料力学特性改变;终板蛋白多糖含量和成分改变可能是颈椎间盘生物力学性能减退的主要原因之一。     

压力可控型椎间盘退变模型的建立及相关研究

[目的]建立压力可控型椎间盘退变模型并进行相关研究.[方法]80只成年大鼠随机分为A、B、C、D 4组,分别模拟人类在站立(A组)、坐位直立(B组)、坐位前屈(C组)3种状态下椎间盘内的压力情况,应用恒定加压装置对第9、10尾椎加压,D组为对照组(一般人椎间盘面积为1 250 mm3,大白鼠为2.8 mm2,人在站立位时椎间盘内压力为500 N,坐位为750 N,坐位前屈为1 350 N,换算成大白鼠椎间盘的压力分别是1.12 N,1.68 N,3.08 N).A、B、C组每日加压4 h,对照组仅在尾椎穿针,不加压;4组分别在7、14 d后取标本进行组织学观察,应用免疫组化和阿利新蓝分析测量胶原纤维(Ⅱ型)和蛋白多糖含量,观察椎间盘退变情况.[结果](1)A组、D组类似,椎间盘组织形态、基质胶原和PG含量和成分无明显变化;(2)C组椎间盘发生软骨细胞变性、坏死,髓核皱缩,纤维环胶原纤维变性、排列紊乱,软骨终板钙化、断裂,胶原纤维排列紊乱等组织形态学改变.髓核和软骨终板中PG总量和Ⅱ型胶原表达下降(P<0.05);(3)B组14 d时形态学未观察到软骨细胞坏死等退变表现,但Ⅱ型胶原以及PG含量比对照组明显减少(P<0.05),退变程度较C组轻.[结论]应用恒定加压装置模拟人类脊柱坐位前屈压力加压大鼠尾椎可迅速建立大鼠椎间盘退变模型.     

微应力下家兔颈椎间盘突出模型的建立

目的 建立一种微应力下家兔颈椎间盘突出模型.方法 家兔随机分组,定制弹簧固定颈6及颈7棘突,分笼饲养3个月建模.对家兔进行X线、MRI检查;取颈椎标本,苏木素-伊红(HE)染色观察相应椎间盘变化.结果 实验组家兔颈椎X线显示内固定物固定良好.颈6/7角度异常,向后成角,前缘可见硬化.MRI显示颈6/7曲度改变,椎间盘T2加权像信号变低;HE染色实验组髓核出现皱缩.髓核体积不断皱缩,并沿纤维环微小裂隙,向后突出.软骨终板层厚度增高.结论 微应力条件可以使家兔颈椎间盘出现退变表现,形成颈椎间盘突出动物模型.     

胶原蛋白酶对兔离体椎间盘类软骨细胞形态学的影响

胶原蛋白酶化学溶解术是一种微创技术,已广泛用于慢性颈腰痛的治疗.椎间盘组织在大体结构上由软骨终板、纤维环和中央的髓核构成;在组织学上由丰富的细胞外基质和散在其中的类软骨细胞构成.细胞外基质主要由水、蛋白多糖和胶原构成,而胶原和蛋白多糖均由类软骨细胞分泌.本课题组前期研究表明,胶原蛋白酶可有效溶解椎间盘组织中的胶原纤维[1].但其对椎间盘组织内细胞学的影响尚不清楚.本研究旨在观察胶原蛋白酶对体外培养的椎问盘类软骨细胞形态学的影响,以探讨胶原蛋白酶的作用机制.     

同种异体椎间盘移植的实验研究

本研究是在自体椎间盘移植实验研究的基础上进一步通过Ｘ线、组织病理、生物学活性、生物化学和生物力学探索异体椎间盘移植是否可存活、功能及其归宿。１２只猴随机分为４组，移植术后３、６、９和１２个月分别处死检测。结果表明移植间盘高度术后下降，但１２个月时仍保持正常高度的６１．４％。光镜下未见明显排斥反应，终板和纤维环结构无明显改变，术后早期可见移植间盘终板软骨增生现象，髓核基质密度增大，成软骨样纤维细胞增生明显。３Ｈ－ｐｒｏｌｉｎｅ掺入较对照组明显增加。术后移植间盘的蛋白多糖和水含量降低，而胶原含量增加。生物力学动态变化表明术后早期移植间盘有失稳趋势，晚期则稳定性恢复。上述结果显示同种异体移植间盘可存活，生化代谢虽有变化但有一定的自限性，形态结构无明显改变，生物力学满足功能需要。     

颈椎间盘退行性疾病

颈椎间盘退行性疾病是以颈椎间盘退变为主所引起的一组疾病。因颈椎间盘退变程度不同可分为 :颈椎间盘膨隆、突出、脱出症。表现为颈椎神经、脊髓、血管等受压的症状、体征。1　颈椎间盘解剖与组织成份颈椎间盘位于Ｃ2 ～Ｔ1的两个椎体间。主要由纤维环和髓核两部分组成 ,软骨终板是否属于椎间盘的构成部分 ,各作者认识有分歧。纤维环呈同心圆行层状结构 ,前侧及两侧较厚 ,后侧较薄 ,各层纤维方向不同 ,彼此呈 3 0°～ 60°交角。纤维环的外层和中层为胶原纤维 ,通过夏贝氏纤维附于椎体骺环 ,内层为纤维软骨 ,附于软骨终板上。髓核位于椎间…     

微生物学因素在椎间盘退变中的研究进展

 腰椎间盘退变是一个多因素参与的慢性过程,现阶段研究发现其发生机制与以下因素相关：（1）老化：随着年龄增长,多种途径导致髓核细胞停止分裂、细胞数量减少、功能下降;（2）代谢相关基因：通过基质金属蛋白酶（matrix metalloproteinase,MMPs）、Sox 基因[3]等调控,导致髓核细胞分泌细胞外基质能力下降,椎间盘逐渐丧失弹性趋向纤维化,产生裂隙;（3）营养：椎间盘作为全身最大的无血供组织,其脆弱的营养弥散途径易受创而难以修复重建;（4）免疫：髓核、Ⅰ、Ⅱ型胶原、软骨终板基质等抗原成分具有自身免疫性,任何原因引起的暴露都将诱发自身免疫椎间盘的早期退变,释放炎性介质产生症状;（5）生物力学：不仅在轴向负荷下,终板易受损、塌陷,在扭转或屈曲的应力负荷下,椎间盘同样将诱发退变的发生。     

椎间盘退变与生物力学

椎间盘退变的因素众多,生物力学是目前学者研究的热点之一。生物力学与椎间盘退变关系密切,可在椎间盘退变基础上进一步加速退变发生进程。生物力可直接使软骨终板发生细胞凋亡并出现Modic退变,也可间接影响椎间盘营养途径。生物力影响椎间盘细胞生物代谢平衡,使细胞内蛋白多糖、胶原纤维及基质金属蛋白酶等物质的合成与分解发生变化,改变椎间盘生物学功能,从而进一步加快椎间盘退变发生进程。     

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.     

Is the recovery profile of mivacurium independent of the rate of decay of its plasma concentration in patients with normal plasma cholinesterase activity?

Background: The duration of action of muscle relaxants is poorly correlated to the rate of decay of their plasma concentration. The plasma concentration of mivacurium may rapidly decrease below its active concentration because of the extensive hydrolysis of mivacurium. By inflating a tourniquet on one upper limb for 3 min after the administration of atracurium, mivacurium or vecuronium, we studied the influence of the initial decline of their plasma concentration on their effect. Methods: In 50 patients anaesthetised with thiopental, isoflurane and fentanyl, the effect of bolus doses of 0.15 or 0.25 mg . kg^?1 mivacurium (MIV 15, MIV 25), 0.3 or 0.5 mg . kg^?1 atracurium (ATR 30, ATR 50) and 0.06 or 0.1 mg . kg^?1 vecuronium (VEC 06, VEC 10) were measured on both arms (evoked response of the adductor pollicis to train-of-four stimulation every 12 s), a tourniquet being applied on one arm just before and during 3 min after the muscle relaxant bolus. Results: Tourniquet inflation of 3 min almost abolished the neuromuscular effect of mivacurium. In the vecuronium groups and in the ATR 50 group, tourniquet inflation did not modify the maximum degree of depression of the twitch response. Also, the duration of action of vecuronium was unaffected by the tourniquet. In the ATR 30 group, times to return of the twitch response to 25% (duration 25%) and 75% (duration 75%) of control response were significantly shorter in the cuffed arm, 23 min vs 27 min, and 41 min vs 45 min, respectively. In the ATR 50 group, only duration 25% was significantly shorter in the cuffed arm (41 min vs 45 min). Conclusion: The results suggest that the rate of decline of the plasma concentration of mivacurium is so rapid, that a very low and almost clinically ineffective concentration is present as soon as 3 min after its administration. The results also indicate that the recovery from a mivacurium-induced neuromuscular blockade is not influenced by the rate of decay of its plasma concentration in patients with genotypically normal plasma cholinesterase.     

Membranes in Artificial Organs

Abstract: Membrane processes play a pivotal and enabling role in modern replacement therapy for acute and chronic organ failure and in the management of immunologic diseases. In fact, virtually all contemporary extracorporeal blood purification methods employ membrane devices, and the next generation of artificial organs and tissue engineering therapies are almost certain to be similarly grounded in membrane technology. In this short essay, we comment on the similarities and differences among synthetic membranes and their natural counterparts and also provide a critical overview of the demographics and technology of hemodialysis, hemofiltration, apheresis, oxygenation, and emerging membrane technologies and applications.     

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.     

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.     

Reduction of Plasma Fibrinogen, Immunoglobulin G, and Immunoglobulin M Concentrations by Immunoadsorption Therapy with Tryptophan and Phenylalanine Adsorbents

Abstract Immunoadsorption (1A) therapy with tryptophan (TR-350) or phenylalanine (PH-350) adsorbents has been used to reduce the concentration of serum antibodies in human lymphocyte antigen (HLA)-immunized patients. Other forms of plasma purification have been reported to reduce the level of fibrinogen, which affects the blood properties. In this study we investigated the effects of IA therapy using both adsorbents on plasma fibrinogen and immunoglobulins G and M in 13 patients (8 patients were treated with TR-350, and 5 patients were treated with PH-350). During each session 1 plasma volume (2.8 ± 0.4 L of plasma) was processed through the immunocolumn and then returned to the patient together with the blood cells. Compared with the pretreatment values, the plasma fibrinogen, IgG, and IgM concentrations were significantly reduced after IA therapy (p < 0.01 for TR-350; p < 0.04 for PH-350). There was a positive correlation between the degree of reduction of plasma proteins and the number of IA treatments given. A nonpara-metric test (Wilcoxon's signed-rank test or the Mann-Whitney test) was used for statistical analysis. We conclude from our study that IA therapy effectively lowers the plasma levels of fibrinogen, IgG, and IgM and thus can be considered a valuable alternative to other blood purification methods.     

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.     

Dilemma of Membrane Biocompatibility and Reuse

Abstract: Numerous articles have been published on the multiple use of dialyzers and on the effect of different reprocessing chemicals and techniques on the dialyzer biocompatibility and performance. The results often appear contradictory, especially those comparing standard biocompatibility parameters. Despite this confusion, a discerning review of the published works allows certain limited conclusions to be drawn. Reprocessing of used hemodialyzers changes the biocompatibility profile of a dialyzer as defined by the parameters complement activation. leukopenia, and cytokine release. The effect of reprocessing depends on the chemicals and reprocessing technique applied and also on the type of membrane polymer being subjected to the reprocessing procedure. Reports of pyrogenic reactions indicate that the flux of the membrane also influences how suitable it is for safe reuse. An increased risk of allergic and pyrogenic reactions appears to be associated with dialyzer reuse. Furthermore, there has been a lack of investigations into the immunologic effect of the layer of adsorbed and chemically altered proteins that remains on the inner surface of reprocessed dialyzers. We conclude that the clinical benefit of dialyzer reuse cannot be generally accepted from a biocompatibility point of view.