超声加热诱导舌鳞癌Tca8113细胞凋亡的机制探讨

目的:通过检测超声加热处理后Tca8113细胞凋亡的主要相关参数变化,探讨超声加热诱导肿瘤细胞凋亡的机制。方法:应用超声热辐射系统,分别对Tca8113细胞进行不同温度、时间的加热处理,流式细胞仪连续检测42℃超声加热10min后Tca8113细胞早期凋亡和继发性坏死的动态变化,以及不同处理组的线粒体跨膜电位(ΔΨm)、Caspase-3活性的变化。采用SAS6.12统计软件包进行方差分析,比较各组均数间的显著性水平。结果:42℃超声加热(10min)Tca8113细胞后1h,即检测到细胞早期凋亡,6～8h达到高峰,以后迅速下降,12h后保持在较低水平,细胞的继发性坏死伴随着凋亡出现,在高水平保持一段时间,10h后开始下降。其与早期凋亡呈正相关(r=0.7909,P=0.0064);无论温度梯度(38℃～44℃,10min)还是时间梯度(42℃,10min～60min)的超声加热,均能导致ΔΨm显著降低(P<0.01)、Caspase-3活性显著升高(P<0.01),且两者具有显著相关性(温度梯度组r=0.89189,P=0.0029,时间梯度组r=0.9679,P=0.0003)。结论:超声加热能诱导Tca8113细胞凋亡,导致ΔΨm降低、Caspase-3活性水平升高。说明超声加热通过线粒体-Caspase途径,诱导Tca8113细胞凋亡。     

Spectroelectrochemical studies of two-dimensional J-aggregates of cyanine dyes organized on chemically modified Au(1 1 1)

High-speed spectroelectrochemical methods—a combination of in situ reflection absorption spectroscopy with a 2 ms time resolution with fast-scan cyclic voltammetry or with a potential step method—allowed comprehensive characterization of the reversible oxidation of two-dimensional (2D) J-aggregates of typical cyanine dyes, which were organized on a cysteamine-modified Au(1 1 1). The in situ absorption spectra proved that the 2D J-aggregate could be oxidized reversibly producing well-dispersed dye positive holes that caused distinct electrochromism in the J-band. The coexisting irreversible mode of J-aggregate oxidation was strongly confined to the aggregate domain edges. Data analysis based on the simple Nernst equation allowed a hitherto difficult assessment of the standard potential of the J-aggregate, and suggested that accumulation of dye positive holes caused strongly non-ideal redox behavior. The standard potential of the J-aggregate shifted negatively with increasing aggregate size, and its systematic change with the level of J-aggregation had a simple linear correlation with the change of light absorption energy. Independent kinetic information on the interfacial electron transfer rate obtained by the potential step method provided additional support for the results of the redox equilibrium analysis and suggested markedly small reorganization energies of around 0.1 eV for the reversible J-aggregate oxidation.     

Double potential step chronoreflectometry approach to bi-stable potential region of the faradaic phase transition of heptyl viologen at a HOPG electrode

The phase transition of an adsorption layer of heptyl viologen (HV) at a basal plane HOPG electrode was investigated using double potential step chrono-reflectometry in the visible wavelength region. For the first order faradaic phase transition between an expanded adsorption layer of oxidized form (HV²⁺) and a two-dimensional (2D) condensed monolayer of reduced form (HV⁺), the nature of the bi-stable potential region was targeted to be explored. The merit of chrono-reflectometry capable of directly tracking the change of 2D superficial fractions of the two phases on the electrode surface was demonstrated experimentally. The double potential step measurements made it possible to gain access to the steady-state coexistence of the two phases in the bi-stable potential region. After the secondary reverse potential step to the positive direction into the bi-stable potential region was given from a transient nucleation state at the first step potential, the superficial fraction of the condensed phase monitored by reflectance was saturated. The plot of this saturated value (φ_dbl) as a function of potential (E) in the bi-stable potential region was found to be dependent on the time period spent at the transient nucleation potential. Therefore, the φ_dbl–E curve thus obtained does not necessarily represent a unique, true equilibrium relationship.     

The reduction of 2-bromomethyl-3-methyl- and 2,3-bis-bromomethyl-1,4-naphthoquinones,potential bioreductive alkylating agents. Electrochemical and computational studies

In the present work, 2,3-dimethyl-1,4-naphthoquinones, substituted at one or both side chains with bromine were prepared and submitted to electrochemical studies (cyclic voltammetry and electrolysis), in aprotic medium (DMF + 0.1 mol l^?1 TBAP), using different electrodes (Hg, GC and Au), to observe the role of bromide, as a good leaving group, in their electroreductions. The cyclic voltammograms are complex. Combined results from CV, chronoamperometry and analysis of the products of electrolysis, mainly dimers and the parent unsubstituted quinone, allowed the qualitative definition of the electrodic mechanism for the reduction of the brominated quinones. A reversible electronic transfer to the quinonoid group followed by the cleavage of C–Br, in an EC type mechanism, more specifically a reductive elimination, is suggested. The quinonoid radical is generated and suffers dimerization to electroactive dimers or a second electron uptake, furnishing the anion that can be protonated to yield 2,3-dimethyl-1,4-naphthoquinone, also electroactive. The additional waves are probably related to the reduction of quinomethide-derived products, upon comparison with a synthetic dimer. Computational studies corroborate the electrochemical observations. Despite the lack of unequivocal proof of quinonemethide generation, its intermediacy is highly probable and this has been proved to be essential for the biological activity of these compounds.     

Role of interleukin-1 and inflammasomes in oral disease

BackgroundInflammation promotes immune cell infiltration into tissues and induces production of pro-inflammatory cytokines that mediate innate immune responses. Acute or temporary inflammation results in the required repair of the inflamed tissues. However, chronic inflammation leads to pathogenesis of inflammatory conditions such as periodontal disease. In periodontal tissues, pro-inflammatory cytokines mediate inflammatory responses and accelerate the bone-resorbing activity of osteoclasts, resulting in destruction of alveolar bone. Levels of interleukin-1 (IL-1), a major pro-inflammatory cytokine that strongly promotes osteoclastic activity, are elevated in oral tissues of patients with periodontitis. Therefore, elucidation of the mechanisms underlying IL-1 production will enhance our understanding of the pathogenesis of periodontal disease.HighlightIL-1 has two isoforms: IL-1α and IL-1β. Both isoforms bind to the same IL-1 receptor and have identical biological activity. Unlike that of IL-1α, the IL-1β precursor is not bioactive. To induce its bioactivity, the IL-1β precursor is cleaved by caspase-1, whose activation is mediated by multiprotein complexes termed inflammasomes. Thus, IL-1β maturation and activity are strictly regulated by inflammasomes. This review highlights the current understanding of the molecular mechanisms underlying IL-1 production and the related inflammasome activity.ConclusionInhibition of IL-1 production or the inflammasomes via their regulatory mechanisms may facilitate prevention or treatment of periodontal disease and other inflammatory diseases.     

长期酒精摄入对小鼠小脑颗粒层场电位的影响及其机制

目的建立小鼠长期酒精注射中毒模型,探讨长期酒精摄入对小鼠小脑皮层苔藓纤维-颗粒细胞感觉信息突触传递的影响机制。方法20只6~8周龄的健康雄性ICR小鼠按照随机数字表法分为生理盐水组(对照组)和酒精摄入组(酒精组),每组10只。酒精摄入组每日腹腔注射浓度为20%的酒精,对照组则注射同等剂量的生理盐水,注射周期均为28 d。注射结束后,在小脑的CrusⅡ区清除头皮及肌肉组织,去除颅骨,剥离硬脑膜,利用气体喷射装置在同侧触须垫30 mm处给予吹风刺激,寻找最大反应部位后,在小鼠脑表面灌流NMDA受体阻断剂[D-(-)-2-amino-5-phosphono-valerate,D-APV]、代谢性谷氨酸受体1阻断剂(JNJ16259685)及N-甲基-D-天冬氨酸(N-Methyl-D-aspartic acid,NMDA),每种药物灌流20 min,两种药物之间用人工脑脊液充分灌流直到波形恢复,期间通过膜片钳技术,记录小鼠小脑颗粒层电位波形的变化特点。采用Clampfit 10.3软件和SPSS 22.0软件对所有实验数据进行统计分析。结果给予吹风刺激后酒精组小鼠颗粒层场电位反应的潜伏期(11.8±0.7)ms较对照组(10.1±0.2)ms显著延长(t=-8.041,P<0.05),N1的振幅(1.2±0.1)mV明显小于对照组(0.6±0.1)mV(t=-12.728,P<0.05)。与对照组比较,酒精组小鼠颗粒层场电位反应抑制性成分P1波形上升时间[(4.4±0.2)ms,(3.2±0.2)ms]、持续时间[(12.1±0.5)ms,(10.3±0.2)ms]、消退时间[(7.8±0.2)ms,(6.9±0.2)ms]、波形下面积[(7.3±0.2)ms,(4.3±0.2)ms]均显著升高(t=16.100,-11.840,-11.673,-35.576,均P<0.05)。而两组小鼠刺激结束反应波形Roff波的振幅、波形半宽值、波形上升时间和衰减时间均差异无统计学意义(t=-1.909,-0.910,-0.789,1.462;均P>0.05)。当酒精组小鼠脑表面灌流JNJ16259685时,给予的5个吹风刺激诱发场电位的振幅较给药前均差异无统计学意义(P>0.05)。酒精组小鼠脑表面灌流D-APV后,吹风刺激诱发的场电位P1的振幅[(42.3±1.5)mV]较给药前[(101.1±0.9)mV]及洗脱后[(100.1±2.2)mV]均显著降低(t=106.762,-69.605;均P<0.05),P1的波形下面积[(42.6±1.3)%]较给药前[(100.6±1.6)%]与洗脱后[(97.6±2.2)%]也显著减小(t=88.862,-67.791;均P<0.05),且N2/N1比值(0.3±0.1)较给药前(0.4±0.1)与洗脱后(0.3±0.1)也明显降低(t=2.242,2.121;均P<0.05)。对照组小鼠脑表面灌流NMDA后,P1的振幅[(110.7±3.2)mV]较给药前[(100.1±0.9)mV]与洗脱后[(102.0±1.7)mV]显著增加(t=-10.173,7.669,均P<0.05),P1的波形下面积[(127.9±3.5)%]较给药前[(100.0±3.1)%]与洗脱后[(115.0±5.3)%]显著升高(t=-18.698,6.447,均P<0.05),而且N2/N1比值(0.5±0.1)较给药前(0.3±0.1)与洗脱后(0.3±0.1)也明显增高(t=-5.669,5.669,均P<0.05)。对照组小鼠脑表面灌流NMDA受体阻断剂D-APV后,面部吹风刺激诱发的场电位与给药前及洗脱后差异无统计学意义(P>0.05)。结论长期酒精摄入显著压制MF-GC兴奋性谷氨酸能突触传递,增强小脑皮层GABAA受体介导的抑制性反应,抑制性成分的增强依赖于NMDA受体,但不依赖于1型代谢性谷氨酸受体。     

银杏叶总黄酮对豚鼠肠系膜下神经节细胞ls-EPSP的影响

目的观察银杏叶总黄酮(TFG)对交感神经节细胞迟慢兴奋性突触后电位(ls-EPSP)的影响并分析其作用的可能机制。方法细胞内记录技术和离体神经节灌流。结果豚鼠肠系膜下神经节(IMG)细胞静息电位为(-53·1±6·5)mV(n=54);重复电刺激(10V,1ms,20Hz,4s)与IMG相连的腹下神经,在IMG有61·1%(33/54)的细胞可诱发ls-EPSP,其电位的幅度与时程分别为(7·7±1·8)mV和(97·4±17·4)s(n=33);用TFG(100~500mg/L)灌流,其中有78·8%(26/33)细胞的ls-EPSP出现抑制,幅度与时程均表现降低和缩短,且表现一定的剂量依赖性;另有21·2%(7/33)的细胞无明显反应。由TFG引起的ls-EPSP抑制可被低钙/高镁Krebs液可逆性阻断,但不受胆碱或肾上腺素受体阻断剂影响;亦可被低钠(58mmol/L)、高钾(20mmol/L)的Krebs液和河豚毒(10μmol/L)所增强,并可被四乙基铵(1mmol/L)所减弱。结论TFG可不同程度抑制IMG内大多数细胞的ls-EPSP,其作用离子机制可能与Na+内流减弱和K+外流增强有关。     

Evidence for a causal relationship between hyperkalaemia and axonal dysfunction in end-stage kidney disease

ObjectivePotassium (K⁺) has been implicated as a factor in the development of uraemic neuropathy. This study was undertaken to investigate whether hyperkalaemia plays a causal role in axonal dysfunction in end-stage kidney disease (ESKD).MethodsMedian motor nerve excitability studies were undertaken in four haemodialysis patients during a modified dialysis session. The serum K⁺ level was “clamped” (fixed) for the first 3 h of dialysis, whilst allowing all other solutes to be removed, this was followed by dialysis against low dialysate K⁺ for a further 4 h. Blood chemistry and nerve excitability studies were undertaken prior to, during and following dialysis. Results were compared to results from the same patients during routine dialysis sessions.ResultsAll patients demonstrated significant nerve excitability abnormalities reflective of nerve membrane depolarization in pre-dialysis recordings (p < 0.01). After the 3 h clamp period, serum K⁺ remained elevated (5.0 mmol/L) and nerve excitability remained highly abnormal, despite the significant clearance of other uraemic toxins. In contrast, studies undertaken during routine dialysis sessions demonstrated significant improvement in both serum K⁺ and nerve function after 3 h.ConclusionsThe current study has established a causal relationship between serum K⁺ and axonal membrane depolarization in haemodialysis patients.SignificanceFrom a clinical perspective, strict K⁺ control may help improve nerve function in ESKD.     

Misinterpretation of sural nerve conduction studies due to anatomical variation

Objective

Anatomical variation of the sural nerve has been documented in numerous cadaver studies. The sural nerve conduction parameters can potentially be influenced by the sural nerve type A formation formed by the union of the medial sural cutaneous nerve (MSCN) and the peroneal communicating branch (PCB) and the type C formation with the sural nerve formed solely by the PCB.

Methods

In 17 out of 240 prospectively examined subjects referred for polyneuropathy a suspicion of an anatomical variation of the sural nerve was raised due to decreased amplitude or substantial side-to-side variation (>50%) of the sensory nerve action potential (SNAP) in disproportion to the clinical findings. To verify the variation the sural nerve was examined further with surface electrodes and near-nerve technique, including extra lateral and distal needle placements.

Results

In all 17 subjects an anatomical variation affecting the sural SNAP was confirmed as a normal sural SNAP could be obtained by changing the electrode placement. The most frequent variation, seen in 15 subjects, was a type A formation with union of the MSCN and the PCB distally at low calf, while a type C formation was seen in 2 subjects.

Conclusions

In case of a decreased sural SNAP amplitude or substantial side-to-side variation in disproportion to the neurologic evaluation, an anatomical variation instead of pathology could be suspected and a different electrode placement be considered.

Significance

Neurophysiologists should be aware of different types of formations of the sural nerve which may cause misinterpretations of nerve conduction studies, especially when needle electrodes are used.