盐酸右美托咪定对缺血-再灌注损伤大鼠心肌Toll样受体4/核因子-κB信号通路的作用

目的研究盐酸右美托咪定对心肌缺血-再灌注损伤大鼠心肌组织中Toll样受体(toll-like receptor,TLR)-4mRNA、核因子(nuclear factor,NF)-κB mRNA的表达,探讨盐酸右美托咪定对心肌缺血-再灌注损伤大鼠心肌TLR-4/NF-κB信号通路的影响。方法健康3个月龄SD雄性大鼠21只,体重250~300g,随机均分为三组:假手术组(sham组)、缺血-再灌注组(IR组)、缺血-再灌注+盐酸右美托咪定组(DEX组)。采用结扎左冠状动脉前降支的方法制备大鼠心肌缺血-再灌注损伤模型,sham组左冠状动脉穿线不结扎。Sham组和IR组在结扎前30min经腹腔注射生理盐水100μg/kg,DEX组在结扎前30min经腹腔注射盐酸右美托咪定注射液100μg/kg(4μg/ml)。实时定量逆转录聚合酶链反应(RT-PCR)方法检测TLR-4mRNA和NF-κB mRNA的表达。结果sham、IR和DEX组的TRL-4mRNA分别为(2.21±0.11)、(7.83±0.35)和(3.91±0.21),sham、IR和DEX组的NF-κB mRNA分别为(0.013±0.166)、(0.051±0.016)和(0.015±0.004),IR、DEX组的TRL-4mRNA和NF-κB mRNA的表达明显高于sham组,且DEX组TRL-4mRNA和NF-κB mRNA的表达明显低于IR组(P0.05)。结论盐酸右美托咪定可降低缺血-再灌注损伤大鼠心肌组织TLR-4mRNA和NF-κBmRNA的表达,盐酸右美托咪定可以调控TLR/NF-κB信号通路的转导,抑制炎症反应,减轻心肌缺血-再灌注损伤,保护心肌。     

右美托咪定对反复缺血-再灌注脑损伤小鼠学习记忆能力的影响

目的探讨右美托咪定对反复缺血-再灌注(IR)脑损伤小鼠学习记忆能力的影响。方法无特定病原体(SPF)级成年C57BL/6J小鼠60只,按照随机数字表法分为四组:右美托咪定25μg/kg组(L组)、右美托咪定50μg/kg组(H组)、缺血-再灌注组(IR组)和假手术组(Sham组),每组15只。L组和H组小鼠分别经腹腔注射右美托咪定25μg/kg、50μg/kg,30min后采用双侧颈总动脉夹闭术,建立反复IR脑损伤模型;IR组小鼠建立反复IR脑损伤模型;Sham组小鼠只分离双侧颈总动脉,但不夹闭。Sham组和IR组小鼠于缺血前30min分别经腹腔注射等容量的生理盐水。采用Morris水迷宫试验测试小鼠术前及术后的学习记忆能力,随后处死小鼠,留取海马组织并测定其湿/干重比(W/D)和总含水量(TCW),采用伊文斯蓝(EB)法检测血脑屏障的通透性。采用逆转录-聚合酶链式反应(RT-PCR)测定海马组织Toll样受体4(TLR4)、核调节因子-κB(NF-κB)mRNA表达水平,采用Western blot测定海马组织TLR4、NF-κB蛋白含量。结果术后3、7dIR组小鼠逃避潜伏期及游泳距离均明显长于Sham组,L组和H组小鼠的逃避潜伏期及游泳距离明显短于IR组(P0.05)。IR组小鼠海马组织W/D、TCW和脑组织EB含量明显高于Sham组,L组和H组小鼠海马组织W/D、TCW和脑组织EB含量明显低于IR组(P0.05)。IR组小鼠海马组织NF-κB mRNA、TLR4mRNA和蛋白表达水平明显高于Sham组,L组和H组小鼠海马组织NF-κB mRNA、TLR4mRNA和蛋白表达水平明显低于IR组,H组小鼠海马组织NF-κB mRNA、TLR4mRNA和蛋白表达水平明显低于L组(P0.05)。结论腹腔注射25μg/kg、50μg/kg的右美托咪定均可改善反复IR脑损伤小鼠的学习记忆能力,其机制可能与其抑制海马组织TLR4和NF-κB表达、减轻脑损伤有关。     

右美托咪定对神经病理性痛大鼠脊髓Toll样受体4和NF-κB表达的影响

目的 评价右美托咪定对神经病理性痛大鼠脊髓Toll样受体4和NF-κB表达的影响.方法 健康成年雄性Wistar大鼠108只,6～8周龄,体重180 ～ 220 g,采用随机数字表法,将其分为3组(n=36):假手术组(S组)、神经病理性痛组(NP组)和右美托咪定组(D组).采用坐骨神经慢性压榨性损伤法制备神经病理性痛模型,D组于术后即刻开始至处死前1d腹腔注射右美托咪定50μg/kg,1次/d.S组和NP组以等容量生理盐水替代.于术前1d,术后3、7、14 d时测定机械痛阈和热痛阈,并于术后测定痛阈后处死,取L4-6脊髓组织,采用RT-PCR法测定TLR4 mRNA和NF-κB mRNA的表达,采用免疫组织化学法测定脊髓背角TLR4和NF-κB的表达水平.结果 与S组比较,NP组和D组机械痛阈和热痛阈降低,TLR4及其mRNA、NF-κB及其mRNA的表达上调(P＜0.05);与NP组比较,D组机械痛阈和热痛阈升高,TLR4及其mRNA、NF-κB及其mRNA的表达下调(P＜0.05).结论 右美托咪定减轻大鼠神经病理性痛的机制与抑制TLR4和NF-κB表达有关.     

不同剂量右美托咪定对创伤性脑损伤大鼠神经炎症反应及神经营养因子的影响

目的 探讨不同剂量右美托咪定对创伤性脑损伤（TBI）大鼠神经炎症反应及神经营养因子的影响。
方法 健康清洁级成年雄性SD大鼠75只,10～12周龄,体重220～250 g。采用随机数字表法将大鼠随机分为五组：假手术组（S组）、TBI组（T组）、右美托咪定25 μg/kg组（D25组）、右美托咪定50 μg/kg组（D50组）和右美托咪定100 μg/kg组（D100组）,每组15只。S组仅行头皮切开钻孔手术,T组采用Feeney自由落体法建立TBI模型,D25组、D50组、D100组分别于TBI模型建立后立即腹腔注射右美托咪定25、50、100 μg/kg。采用改良神经功能缺损评分（mNSS）评估建模后12、24、48、72 h的神经功能,干/湿比重法检测脑组织含水量,Western blot法检测脑组织肿瘤坏死因子-α（TNF-α）、白细胞介素-1β （IL-1β）及白细胞介素-6(IL-6)蛋白含量,免疫组织化学染色法观察脑组织皮层区脑源性生长因子（BDNF）、神经生长因子（NGF）表达情况。
结果 与S组比较,T组不同时点mNSS明显升高（P<0.05）,脑组织含水量明显增多（P<0.05）,脑组织TNF-α、IL-1β、IL-6蛋白含量明显升高（P<0.05）,脑组织皮层区BDNF、NGF表达及阳性细胞数明显增多（P<0.05）。与T组比较,D25组、D50组、D100组mNSS明显降低（P<0.05）,脑组织含水量明显减少（P<0.05）,脑组织TNF-α、IL-1β、IL-6蛋白含量明显降低（P<0.05）,脑组织皮层区BDNF、NGF表达及阳性细胞数明显增多（P<0.05）。与D25组比较,D50组不同时点mNSS明显降低（P<0.05）,脑组织含水量明显减少（P<0.05）,脑组织TNF-α、IL-1β、IL-6蛋白含量明显降低（P<0.05）,脑组织皮层区BDNF、NGF表达及阳性细胞数明显增多（P<0.05）。D25组、D100组各指标差异无统计学意义。
结论 相对于右美托咪定25和100 μg/kg,右美托咪定50 μg/kg腹腔注射可明显改善脑水肿,减轻神经炎症反应,增加TBI后皮层神经营养因子表达水平,缓解神经功能障碍。     

右美托咪定对全脑缺血再灌注大鼠血脑屏障通透性的影响

目的 评价右美托咪定对全脑缺血再灌注大鼠血脑屏障通透性的影响.方法 成年雄性SD大鼠36只,体重250 ～ 300 g,采用随机数字表法,将其分为3组(n=12):假手术组(S组)、全脑缺血再灌注组(I/R组)和右美托咪定组(D组).采用夹闭双侧颈总动脉联合低血压法建立大鼠全脑缺血再灌注损伤模型.D组于再灌注即刻经颈总静脉注射右美托咪定3 μg/kg负荷剂量,后以3μg·kg-1·h-1的速率静脉输注至再灌注2h.再灌注24h时,处死大鼠,取脑组织,观察海马CAI区病理学结果,测定细胞凋亡水平、脑含水量、脑组织伊文氏蓝(EB)含量和水通道蛋白4(AQP4)的表达.结果 与S组比较,I/R组和D组细胞凋亡增加,脑含水量和脑组织EB含量升高,AQP4表达上调(P＜ 0.05或0.01);与I/R组比较,D组细胞凋亡减少,脑含水量和脑组织EB含量降低,AQP4表达下调(P＜ 0.05或0.01),病理学损伤减轻.结论 右美托咪定可降低血脑屏障通透性,减轻大鼠全脑缺血再灌注损伤,其机制可能与下调AQP4的表达有关.     

右美托咪定对丙泊酚或七氟醚全麻患者脑状态指数的影响

目的观察右美托咪定对全麻患者脑状态指数的影响。方法选择择期上腹部手术的全麻患者80例,男39例,女41例,年龄25~65岁,ASAⅠ或Ⅱ级。所有患者分为四组:丙泊酚组(P组),靶控输注丙泊酚血浆浓度3.0~4.0μg/ml;丙泊酚+右美托咪定组(PD组),靶控输注丙泊酚血浆浓度1.5~2.5μg/ml,右美托咪定0.5μg/kg,输注5 min,再持续输注0.6μg·kg~(-1)·h~(-1);七氟醚组(S组),吸入1.5%~2.5%七氟醚;七氟醚+右美托咪定组(SD组),吸入1%~1.5%七氟醚,右美托咪定0.5μg/kg,输注5min,再持续输注0.6μg·kg~(-1)·h~(-1)。术中所有患者镇静指数维持在45~55。分别于麻醉前、右美托咪定持续输注30、60min测定脑状态指数(记忆加工指数、谵妄指数)。结果麻醉前四组脑状态指数差异无统计学意义。右美托咪定持续输注30、60 min时PD组记忆加工指数和谵妄指数均明显低于P组(P0.05),SD组均明显低于S组(P0.05)。结论全麻中复合应用右美托咪定能够降低患者的脑状态指数。     

不同剂量右美托咪定预处理对大鼠全脑缺血再灌注损伤炎性反应的影响

目的观察不同剂量右美托咪定预处理对大鼠全脑缺血再灌注损伤炎性反应的影响。方法全脑缺血前2 h,假手术组(S组),对照组(C组)静注生理盐水2mL/h,低剂量右美托咪定预处理组(D1组)、高剂量右美托咪定预处理组(D2组)分别静注右美托咪定每分钟0.05μg/kg和每分钟0.5μg/kg。全脑缺血再灌后30分钟检测血清肿瘤坏死因子(TNF)-α和白细胞介素(IL)-1β变化;测定脑组织含水量;观察海马CA1区神经病理变化。结果与C组比较,D1组、D2组TNF-α、IL-1β水平显著减少(P0.05),D1组、D2组之间比较差异无统计学意义(P0.05)。D1组、D2组较C组固缩神经元数量及神经元缺失显著减少。结论全脑缺血再灌注损伤大鼠,低、高剂量右美托咪定预处理均可产生一定的脑保护作用。     

右美托咪定对丙泊酚麻醉新生大鼠海马PI3K／Akt信号通路的影响

目的探讨右美托咪定对丙泊酚麻醉新生大鼠海马磷脂酰肌醇3激酶/蛋白激酶B(phosphoinositide 3-kinase/protein kinase B,PI3K/Akt)信号通路的影响。方法雄性SD大鼠80只,日龄7d,体重10~15g,随机分为八组:生理盐水组(N组)、脂肪乳剂组(I组)、二甲基亚砜(DMSO)组(D组)、丙泊酚100mg/kg组(P组)、右美托咪定25μg/kg+丙泊酚100mg/kg组(PD25组)、右美托咪定50μg/kg+丙泊酚100mg/kg组(PD50组)、右美托咪定75μg/kg+丙泊酚100mg/kg组(PD75组)和LY294002 25μg+右美托咪定75μg/kg+丙泊酚100mg/kg组(LYPD组),每组10只。于大鼠苏醒2h后,每组取5只用透射电镜观察海马神经元的形态学变化,剩余5只采用Western blot法检测海马Akt和pAkt(ser473)蛋白含量。结果八组大鼠Akt蛋白含量差异无统计学意义。P组、PD25组、PD50组、PD75组和LYPD组pAkt(ser473)蛋白含量明显低于N组(P0.05);PD75组和LYPD组pAkt(ser473)蛋白含量明显高于P组(P0.05);LYPD组pAkt(ser473)蛋白含量明显低于PD75组(P0.05)。N组、I组、D组大鼠海马神经元的形态结构基本正常;P组大鼠海马神经元出现细胞核明显肿胀、染色质密度降低、线粒体空泡化等细胞结构损伤表现;PD25组、PD50组、PD75组大鼠海马神经元细胞结构损伤随着右美托咪定剂量的增加而减轻;LYPD组大鼠海马神经元细胞核固缩,核膜部分溶解,染色质凝聚,线粒体明显空泡变性。结论右美托咪定减轻丙泊酚对发育期大鼠海马神经元的损伤,其机制可能与其减弱丙泊酚对PI3K/Akt信号通路的抑制有关。     

右美托咪定与丙泊酚麻醉诱导时的协同作用

目的评价右美托咪定和丙泊酚麻醉诱导时镇静作用的相互影响。方法择期全麻手术患者75例,男36例,女39例,年龄18～65岁,BMI 20～25kg/m~2,ASAⅠ或Ⅱ级,采用随机数字表法均分为三组,每组25例:丙泊酚组(A组)、右美托咪定组(B组)、丙泊酚复合右美托咪定组(C组),每组再根据不同药物剂量分为5个亚组,相邻两组剂量等比为1.25,采用点斜法计算ED_(50)及其95%可信区间(CI)。结果A组丙泊酚诱导剂量ED_(50)为1.25 mg/kg(95%CI 0.90～1.45mg/kg),B组右美托咪定麻醉诱导剂量ED_(50)为1.35μg/kg(95%CI 0.95～1.50μg/kg),C组丙泊酚和右美托咪定诱导剂量ED_(50)分别为0.65mg/kg(95%CI 0.50～0.90mg/kg)和0.40μg/kg(95%CI 0.34～0.65μg/kg)。等辐射分析法判定丙泊酚和右美托咪定之间在镇静效应上呈现协同作用。结论右美托咪定复合丙泊酚可以产生明显的镇静效应协同作用。     

不同剂量右美托咪定对琥珀胆碱气管插管时眼内压的影响

目的观察不同剂量右美托咪定对琥珀胆碱气管插管引起的眼内压(IOP)升高的影响。方法选择ASAⅠ或Ⅱ级无眼部疾患的全麻患者60例,随机均分为三组:D1组和D2组,麻醉诱导前10min内分别静脉给予右美托咪定0.4、0.6μg/kg;C组,给予等量生理盐水。监测和记录给予右美托咪定前(基础值,T0)、给予右美托咪定后3min(T1)、麻醉诱导后30s(T2)、给予琥珀胆碱后30s(T3)、气管插管后1min(T4)、2min(T5)、4min(T6)和6min(T7)时的MAP、HR和IOP。结果给予右美托咪定后D2组有2例患者因出现低血压和心动过缓被排除本研究。与T0时比较,T1～T3时D1组和D2组IOP明显降低(P<0.05);C组T3～T7时IOP和T4～T7时MAP明显升高;T4～T6时HR明显增快(P<0.05)。与C组比较,T3～T7时D1、D2组IOP明显降低(P<0.05),T4～T7时D1、D2组MAP明显降低、HR明显减慢(P<0.05)。结论静脉给予右美托咪定0.4、0.6μg/kg可有效预防与琥珀胆碱和气管插管有关的IOP升高,但0.6μg/kg右美托咪定可引起明显的低血压和心动过缓。因此,建议术前应用0.4μg/kg右美托咪定预防IOP升高。     

Asymptomatic brain tumor detected at brain check-up

Brain check-up was performed in 4000 healthy subjects who underwent medical and radiological examinations for possible brain diseases in our hospital from April 1996 to March 2000. Magnetic resonance imaging revealed 11 brain tumors which consisted of six meningiomas, three pituitary adenomas, one astrocytoma, and one epidermoid cyst. The detection rate of incidental brain tumor in our hospital was 0.3%. Nine patients underwent surgery, with one case of morbidity due to postoperative transient oculomotor nerve paresis. The widespread use of brain check-up may increasingly detect asymptomatic brain tumors. Surgical indications for such lesions remain unclear, and the strategy for treatment should be determined with consideration of the patient's wishes.     

Effect of AVP on brain edema following traumatic brain injury

Objective: To evaluate plasma arginine vasopressin (AVP) level in patients with traumatic brain injury and investigate the role of AVP in the process of brain edema. Methods: A total of 30 patients with traumatic brain injury were involved in our study. They were divided into two groups by Glasgow Coma Scale: severe traumatic brain injury group (STBI, GCS≤8) and moderate traumatic brain injury group ( MTBI, GCS >8). Samples of venous blood were collected in the morning at rest from 15 healthy volunteers (control group) and within 24 h after traumatic brain injury from these patients for AVP determinations by radioimmunoassay. The severity and duration of the brain edema were estimated by head CT scan. Results: plasma AVP levels (ng/L) were (mean±SD): control, 3. 06±1. 49; MTBI, 38. 12±7. 25; and STBI, 66. 61±17. 10. The plasma level of AVP was significantly increased within 24 h after traumatic brain injury and followed by the reduction of GCS, suggesting the deterioration of cerebral injury (P<0. 01). And the AVP level was correlated with the severity (STBI r =0.919, P < 0.01; MTBI r = 0.724, P < 0.01) and the duration of brain edema (STBI r = 0. 790, P < 0. 01; MTBI r = 0. 712, P<0.01). Conclusions: The plasma AVP level is closely associated with the severity of traumatic brain injury. AVP may play an important role in pathogenesis of brain edema after traumatic brain injury.     

Clinical application of brain hypothermia therapy for acute brain insults

Brain hypothermia therapy has been expected to lead to good neurological outcome in acute brain insults. There are a few positive results which have been proven by multicenter randomized clinical trials (RCT) in the cardiopulmonary arrest (CPA) in patients with ventricular fibrillation. Among these clinical trials, early application of hypothermia, maintenance of cerebral blood flow during hypothermia therapy and prevention of quick rewarming are pointed out to result in good outcome from clinical experiences. For brain hypothermia therapy to become an effective method for acute brain insults, indications, brain oriented intensive cares and biomarkers for the therapy must be established. RCT in acute brain insults beside CPA victims are needed in the near future.     

Assessment of brain shift related to deep brain stimulation surgery

Deep brain stimulation (DBS) surgery can significantly improve the quality of life for patients suffering from movement disorders, but the success of the procedure depends on the implantation accuracy of the DBS electrode array. Pre-operative surgical planning and navigation are based on the assumption that the brain tissue is rigid between the time of the acquisition of the pre-operative image set and the time of surgery. A shift of deep brain structures by only a few millimeters can potentially increase the number of required microelectrode and/or macroelectrode tracks and decrease implantation accuracy. We studied 25 subjects that underwent DBS surgery and analyzed brain shift between pre-operative and post-operative 3D MRI scans. Brain shift of up to 4 mm was observed in deep brain structures. On average, the recorded shift was in the direction of gravity, with deeper structures experiencing smaller shift than more superficial structures. The main conclusion of the study is that the brain shift is comparable to the size of the targets in deep brain stimulation surgery and should not be ignored. Techniques that minimize the amount of brain shift may therefore lead to increased accuracy of DBS lead implantation.     

Comparison of stereotactic brain biopsy to interventional magnetic-resonance-imaging-guided brain biopsy

Lesions within the brain are commonly sampled using stereotactic techniques. The advent of interventional magnetic resonance (MR) imaging now allows neurosurgeons to interactively investigate specific regions with exquisite visualization. We compared the safety and efficacy of this new surgical approach with stereotaxis. From February 1991 to June 1998, 134 stereotactic and 35 interventional MR-guided brain biopsies were performed. Stereotactic biopsies utilized preoperative scanning. Interactive scanning was used to confirm accurate positioning of the biopsy needle within the region of interest. Intraoperative pathologic examination of biopsy material was performed to verify the presence of diagnostic tissue in both biopsy groups. Intra- and postoperative MR imaging was obtained to exclude the presence of intraoperative hemorrhage. Recently, MR spectroscopic targeting has been utilized in 6 patients. In the stereotactic group, 129/134 (96%) biopsies were diagnostic. One patient had a transient hemiparesis after a brain stem biopsy and another suffered a fatal hemorrhage for a morbidity rate of 0.7% and a mortality rate of 0.7%. In reviewing 7,471 stereotactic biopsies, the morbidity was 3.5%, mortality 0.7% and diagnostic yield 91%. All 35 MR-guided brain biopsies were diagnostic (100%). MR spectroscopy was accurate in all cases in distinguishing recurrent tumor (5 cases) from radiation necrosis (1 case). One patient (3%) suffered a transient hemiparesis following a pontine biopsy and another patient (3%) developed a postoperative scalp cellulitis. No patient sustained a clinically or radiologically significant hemorrhage as determined by the immediate postbiopsy, intraoperative MR imaging. Interventional MR-guided brain biopsy is a safe and effective technique for evaluating lesions of the brain with morbidity and mortality rates comparable to those of stereotaxis. MR-guided biopsy appears to have a higher diagnostic yield than stereotaxis, which may reflect the ability to perform interactive, intraoperative scanning with that technique.