Anesthetic effects on the structure and dynamics of the second transmembrane domains of nAChR α4β2

Channel functions of the neuronal α4β2 nicotinic acetylcholine receptor (nAChR), one of the most widely expressed subtypes in the brain, can be inhibited by volatile anesthetics. Our Na⁺ flux experiments confirmed that the second transmembrane domains (TM2) of α4 and β2 in 2:3 stoichiometry, (α4)₂(β2)₃, could form pentameric channels, whereas the α4 TM2 alone could not. The structure, topology, and dynamics of the α4 TM2 and (α4)₂(β2)₃ TM2 in magnetically aligned phospholipid bicelles were investigated using solid-state NMR spectroscopy in the absence and presence of halothane and isoflurane, two clinically used volatile anesthetics. ²H NMR demonstrated that anesthetics increased lipid conformational heterogeneity. Such anesthetic effects on lipids became more profound in the presence of transmembrane proteins. PISEMA experiments on the selectively ¹⁵N-labeled α4 TM2 showed that the TM2 formed transmembrane helices with tilt angles of 12° ± 1° and 16° ± 1° relative to the bicelle normal for the α4 and (α4)₂(β2)₃ samples, respectively. Anesthetics changed the tilt angle of the α4 TM2 from 12° ± 1° to 14° ± 1°, but had only a subtle effect on the tilt angle of the (α4)₂(β2)₃ TM2. A small degree of wobbling motion of the helix axis occurred in the (α4)₂(β2)₃ TM2. In addition, a subset of the (α4)₂(β2)₃ TM2 exhibited counterclockwise rotational motion around the helix axis on a time scale slower than 10^- 4 s in the presence of anesthetics. Both helical tilting and rotational motions have been identified computationally as critical elements for ion channel functions. This study suggested that anesthetics could alter these motions to modulate channel functions.     

Effects of the anesthetic agent propofol on neural populations

The neuronal mechanisms of general anesthesia are still poorly understood. Besides several characteristic features of anesthesia observed in experiments, a prominent effect is the bi-phasic change of power in the observed electroencephalogram (EEG), i.e. the initial increase and subsequent decrease of the EEG-power in several frequency bands while increasing the concentration of the anaesthetic agent. The present work aims to derive analytical conditions for this bi-phasic spectral behavior by the study of a neural population model. This model describes mathematically the effective membrane potential and involves excitatory and inhibitory synapses, excitatory and inhibitory cells, nonlocal spatial interactions and a finite axonal conduction speed. The work derives conditions for synaptic time constants based on experimental results and gives conditions on the resting state stability. Further the power spectrum of Local Field Potentials and EEG generated by the neural activity is derived analytically and allow for the detailed study of bi-spectral power changes. We find bi-phasic power changes both in monostable and bistable system regime, affirming the omnipresence of bi-spectral power changes in anesthesia. Further the work gives conditions for the strong increase of power in the δ-frequency band for large propofol concentrations as observed in experiments.     

Fruit fly behavior in response to chemosensory signals

An important question in contemporary sensory neuroscience is how animals perceive their environment and make appropriate behavioral choices based on chemical perceptions. The fruit fly Drosophila melanogaster exhibits robust tastant and odor-evoked behaviors. Understanding how the gustatory and olfactory systems support the perception of these contact and volatile chemicals and translate them into appropriate attraction or avoidance behaviors has made an unprecedented contribution to our knowledge of the organization of chemosensory systems. In this review, I begin by describing the receptors and signaling mechanisms of the Drosophila gustatory and olfactory systems and then highlight their involvement in the control of simple and complex behaviors. The topics addressed include feeding behavior, learning and memory, navigation behavior, neuropeptide modulation of chemosensory behavior, and I conclude with a discussion of recent work that provides insight into pheromone signaling pathways.     

胸段硬膜外麻醉的研究进展及应用

硬膜外应用局麻药为手术提供麻醉与镇痛,同时胸段硬膜外麻醉与镇痛也被广泛应用于心脏,大血管,胸部和腹部的手术中.它不仅可以加快病人麻醉后的苏醒,而且可以提供很好的术后镇痛.除了上述优点,许多基础及临床研究发现硬膜外麻醉还有许多其它方面的作用,如:减轻神经内分泌系统的应激反应、减少围术期并发症的发生,以及通过暂时性的阻滞胸交感神经提供心肺及胃肠道的保护作用,改善免疫和凝血功能.本文就近年来胸段硬膜外麻醉应用及研究进展作一综述.     

全程心理疏导预防全麻术后导尿管刺激躁动的临床观察

目的:评价全程心理疏导预防全身麻醉术后导尿管刺激躁动的临床效果。方法:全麻下实施胆囊切除手术的80例男性患者为观察对象,随机均分为全程心理疏导组(Ⅰ组)和对照组(Ⅱ组),每组40例。Ⅰ组:术前、麻醉诱导前、苏醒后均对患者施行个体化心理疏导,根据患者具体情况进行沟通,解除其焦虑与恐惧心理。Ⅱ组:常规访视,不进行全程心理疏导。飞利浦多功能监测仪连续监测ECG、HR、SpO2及每3分钟监测一次BP,记录入室后MAP、HR的基础值(T0)、术毕(T1)、拔管后3 min(T2)、10 min(T3)、20min(T4)的血流动力学变化,观察记录拔管后患者因尿管刺激引发躁动评分。结果:Ⅰ组患者苏醒期对尿管刺激反应程度明显低于Ⅱ组,患者在苏醒期血压、心率也较稳定。结论:全程心理疏导可以预防、减轻全麻术后因导尿管刺激而引发的躁动。     

不同麻醉方式对子宫切除患者血液动力学的影响*

目的:探索全麻复合硬膜外麻醉和全身麻醉用于子宫切除术对血液动力学的影响。方法:36例行子宫切除术患者,随机分成全麻组(A组,18例)和硬膜外+全麻组(B组,18例),采用Swan-Ganz导管技术,监测手术时血液动力学变化。结果:A组HR、MAP、CVP、SVR及CI均明显增加,SV无明显变化;B组除CVP明显上升外,其余各指标均无明显变化。结论:全麻复合硬膜外麻醉下施行子宫切除术,能减轻术中应激反应,稳定血液动力学。     

USE OF MIDAZOLAM/PETHIDINE AND TILETAMINE/ZOLAZEPAM COMBINATIONS FOR THE CHEMICAL RESTRAINT OF LEOPARD SEALS (HYDRURGA LEPTONYX)

We immobilized 200–550-kg leopard seals ( Hydrurga leptonyx ) on sea ice in Prydz Bay, Antarctica (68°25'S, 77°10'E) between November 1997 and February 2000. Midazolam (0.18–0.27 mg/kg)/ pethidine (1.0–1.5 mg/kg) was administered by dart to 16 leopard seals. Unpredictable immobilization, poor airway maintenance, and our inability to fully assess the suitability of flumazenil (0.003–0.01 mg/kg), naloxone (0.01–0.013 mg/kg), and naltrexone (0.05–0.12 mg/kg) as reversal agents limited suitability of midazolam/pethidine. Tiletamine/zolazepam 1:1 (0.5–1.5 mg/kg) was, therefore, administered to 19 leopard seals. It produced faster induction (19 ± 3 min), more effective and reliable response to dose (rank correlation: r _s= 0.88, n = 18), and better pulmonary ventilation and faster return of cognitive function upon recovery, in comparison to midazolam/pethidine. Best results were achieved with tiletamine/zolazepam (1.2–1.4 mg/kg) which safely immobilized seven of nine seals for 20–30 min. Entry to the water upon darting was minimized, but not eliminated, by the use of lightweight air-pressurized darts and a thorough knowledge of leopard seal behavior.     

Efficacy of liposome-encapsulated mepivacaine for infiltrative anesthesia in volunteers

This blinded crossover study evaluated the efficacy and pain sensitivity evoked by a previously reported liposome-encapsulated mepivacaine formulation (). Thirty healthy volunteers received an intraoral injection (1.8?mL), at four different sessions, of the following formulations: 2% mepivacaine with 1:100,000 epinephrine (MVC_2%EPI), 3% mepivacaine (MVC_3%), and 2 and 3% liposome-encapsulated mepivacaine (MVC_2%LUV and MVC_3%LUV). Latency period and duration of anesthesia were assessed by an electrical pulp tester and injection discomfort by a visual analog scale (VAS). Data were analyzed with Tukey-Kramer and Friedman tests (P?<?0.05). No significant difference was found regarding latency period (in minutes) among the formulations (P?>?0.05). The duration of anesthesia after the injection of MVC_3%LUV was higher than the one obtained after the infiltration of MVC_2%LUV and of MVC_3% (P?<?0.05). However, the duration of anesthesia obtained with MVC_3% did not differ from the one obtained with MVC_2%LUV (P?>?0.05). MVC_3%LUV showed lower VAS median values than MVC_2%EPI (P?<?0.05), and there were no significant differences among the others formulations. Liposome-encapsulated 3% mepivacaine showed longer duration of anesthesia, in comparison to the commercial formulation of MVC_3%. MVC_2%LUV was able to produce a similar duration of anesthesia as the 3% commercial formulation, despite the 50% decrease in the anesthetic concentration. Thus, the encapsulation of mepivacaine increased the duration of anesthesia and reduced the injection discomfort caused by vasoconstrictor-associated formulations in healthy volunteers.     

右美托咪定联合瑞芬太尼对全身麻醉下髋关节置换术患者脑氧代谢、血流动力学和认知功能的影响

摘要 目的：瑞芬太尼、右美托咪定对全身麻醉下髋关节置换术患者的脑氧代谢、血流动力学和认知功能的影响。方法：选取2016年6月~2019年10月期间我院收治的100例行髋关节置换术的患者。采用随机数字表法分为对照组和研究组,各50例。对照组患者麻醉中予以瑞芬太尼,研究组则在对照组的基础上复合右美托咪定,比较两组患者血流动力学、脑氧代谢和认知功能情况,记录两组患者围术期间不良反应发生率。结果：两组手术开始后30 min（T1）~手术结束时（T2）时间点平均动脉压（MAP）、心率（HR）均呈下降趋势,但研究组高于对照组（P<0.05）。两组T1~T2时间点动脉血氧含量（CaO₂）、颈内静脉血氧含量（CjvO₂）均呈下降趋势,且研究组低于对照组（P<0.05）;两组T1~T2时间点颈静脉球部血氧饱和度（SjvO₂）呈升高趋势,且研究组高于对照组（P<0.05）。两组术前~术后7 d简明精神状态量表（MMSE）评分均呈下降后升高趋势（P<0.05）;研究组术后3 d、术后7 d MMSE评分高于对照组（P<0.05）。研究组术后3 d、术后7 d的认知功能障碍（POCD）发生率低于对照组（P<0.05）。两组不良反应发生率比较无差异（P>0.05）。结论：全身麻醉下髋关节置换术患者麻醉方案选用右美托咪定联合瑞芬太尼,可减轻血流动力学波动,维持脑氧供需平衡,可减少POCD发生风险,且安全性较好。     

超声引导下QLB复合气管插管全麻对于老年患者TEP腹股沟疝无张力修补术影响因素分析

摘要 目的：探讨与分析超声引导下腰方肌阻滞(quadratus lumborum block,QLB)复合气管插管全麻对于老年患者腹腔镜下全腹膜外（totally extraperitoneal prosthetic,TEP）腹股沟疝无张力修补术的影响,以促进该方法的临床使用。方法：2014年9月到2020年6月选择在本院诊治的腹股沟疝老年患者180例,根据随机数字表法分为QLB组与对照组各90例。所有患者都给予腹腔镜下全腹膜外腹股沟疝无张力修补术,对照组给予气管插管全麻,QLB组在对照组麻醉的基础上给予超声引导下QLB,记录两组镇痛与麻醉效果。结果：两组的术中出血量、手术时间等对比差异无统计学意义(P>0.05),QLB组的术后住院时间、术后胃肠功能恢复时间、术后下床活动时间显著短于对照组(P<0.05)。与术后12 h对比,两组术后24 h与36 h的疼痛VAS评分均降低(P<0.05),且QLB组术后12 h、24 h与36 h的疼痛VAS评分都显著低于对照组(P<0.05)。QLB组术后7 d的血肿、呼吸抑制、脏器损伤、腹股沟区包块等并发症发生率为8.9 %,显著低于对照组的21.1 %(P<0.05)。QLB组的瑞芬太尼用量、术后48 h内有效按压自控静脉镇痛泵次数、自控静脉镇痛泵累计用量都显著少于对照组(P<0.05)。结论：超声引导下QLB复合气管插管全麻在老年患者腹腔镜下全腹膜外腹股沟疝无张力修补术中的应用能提高镇痛与麻醉效果,减少术后并发症的发生,有利于促进患者康复。