Brilliance型16排螺旋CT的故障分析与维修

针对日常使用中遇到的Brilliance 16排螺旋CT高压系统、机架以及控制器局域网络(CAN)通讯等故障现象进行分析与维修,最终通过更换滤波电容、机架数据采集控制器(DMC)电源以及信号刷等配件得以排除故障。通过对故障准确判断以及合理运用厂家Service模式下的维修工具软件快速解决故障,保障了影像科检查工作的顺利进行,从而提高设备的稳定性。     

Focal hole versus screw stimulation to prevent false negative results in detecting pedicle breaches during spinal instrumentation

ObjectiveWe describe a stimulus-evoked EMG approach to minimize false negative results in detecting pedicle breaches during lumbosacral spinal instrumentation.MethodsIn 36 patients receiving 176 lumbosacral pedicle screws, EMG threshold to nerve root activation was determined using a focal probe inserted into the pilot hole at a depth, customized to the individual patients, suitable to position the stimulating tip at the point closest to the tested nerve root. Threshold to screw stimulation was also determined.ResultsMean EMG thresholds in 161 correctly fashioned pedicle instrumentations were 7.5 mA ± 2.46 after focal hole stimulation and 21.8 mA ± 6.8 after screw stimulation. Direct comparison between both thresholds in individual pedicles showed that screw stimulation was always biased by an unpredictable leakage of the stimulating current ranging from 10 to 90%. False negative results were never observed with hole stimulation but this was not true with screw stimulation.ConclusionsFocal hole stimulation, unlike screw stimulation, approaches absolute EMG threshold as shown by the lower normal limit (2.6 mA; p < 0.05) that borders the upper limit of threshold to direct activation of the exposed root.SignificanceThe technique provides an early warning of a possible pedicle breakthrough before insertion of the more harmful, larger and threaded screw.     

Excitability of motor and sensory axons in multifocal motor neuropathy

ObjectiveTo assess excitability differences between motor and sensory axons of affected nerves in patients with multifocal motor neuropathy (MMN).MethodsWe performed motor and sensory excitability tests in affected median nerves of 20 MMN patients and in 20 age-matched normal subjects. CMAPs were recorded from the thenar and SNAPs from the 3rd digit. Clinical tests included assessment of muscle strength, two-point discrimination and joint position.ResultsAll MMN patients had weakness of the thenar muscle and normal sensory tests. Motor excitability testing in MMN showed an increased threshold for a 50% CMAP, increased rheobase, decreased stimulus-response slope, fanning-out of threshold electrotonus, decreased resting I/V slope, shortened refractory period, and more pronounced superexcitability. Sensory excitability testing in MMN revealed decreased accommodation half-time and S2-accommodation and less pronounced subexcitability. Mathematical modeling indicated increased Barrett-Barrett conductance for motor fibers and increase in internodal fast potassium conductance for sensory fibers.ConclusionsExcitability findings in MMN suggest myelin sheath or paranodal seal involvement in motor fibers and, possibly, paranodal detachment in sensory fibers.SignificanceExcitability properties of affected nerves in MMN differ between motor and sensory nerve fibers.     

Interactions with PDZ proteins diversify voltage‐gated calcium channel signaling

Voltage‐gated Ca²⁺ (Ca_V) channels are crucial for neuronal excitability and synaptic transmission upon depolarization. Their properties in vivo are modulated by their interaction with a variety of scaffolding proteins. Such interactions can influence the function and localization of Ca_V channels, as well as their coupling to intracellular second messengers and regulatory pathways, thus amplifying their signaling potential. Among these scaffolding proteins, a subset of PDZ (postsynaptic density‐95, Drosophila discs‐large, and zona occludens)‐domain containing proteins play diverse roles in modulating Ca_V channel properties. At the presynaptic terminal, PDZ proteins enrich Ca_V channels in the active zone, enabling neurotransmitter release by maintaining a tight and vital link between channels and vesicles. In the postsynaptic density, these interactions are essential in regulating dendritic spine morphology and postsynaptic signaling cascades. In this review, we highlight the studies that demonstrate dynamic regulations of neuronal Ca_V channels by PDZ proteins. We discuss the role of PDZ proteins in controlling channel activity, regulating channel cell surface density, and influencing channel‐mediated downstream signaling events. We highlight the importance of PDZ protein regulations of Ca_V channels and evaluate the link between this regulatory effect and human disease.     

Activation of voltage‐gated sodium current and inhibition of erg‐mediated potassium current caused by telmisartan,an antagonist of angiotensin II type‐1 receptor,in HL‐1 atrial cardiomyocytes

Telmisartan (TEL) is a non‐peptide blocker of angiotensin II type‐1 (AT₁) receptor. However, the mechanisms through which this drug interacts directly with ion currents in hearts remain largely unclear. Herein, we aim to investigate the effects of TEL the on ionic currents and membrane potential of murine HL‐1 cardiomyocytes. In whole‐cell recordings, addition of TEL stimulated the peak and late components of voltage‐gated Na⁺ currents (I_Na) with different potencies. The EC₅₀ values required to achieve the stimulatory effect of this drug on peak and late I_Na were 0.2 and 1.2 μmol/L, respectively, and the current‐voltage relationship of peak I_Na shifted toward less‐depolarized potentials during exposure to TEL. Telmisartan not only increased peak I_Na but also prolonged the inactivation time course of late I_Na. Amiodarone (Amio) or ranolazine (Ran), but not angiotensin II, could reverse TEL‐mediated effects. The drug enhanced the recovery rate of I_Na inactivation and exerted an inhibitory effect on erg‐mediated K⁺ and L‐type Ca²⁺ currents. In whole‐cell current‐clamp recordings, addition of the drug resulted in prolongation of the duration of action potentials (APs) in a dose‐dependent manner in HL‐1 cells; Amio or Ran could reverse this increase in AP durations. Telmisartan‐mediated prolongation of AP was attenuated in KCNH2 siRNA‐transfected HL‐1 cells. In cultured smooth muscle cells of the human coronary artery, TEL enhanced I_Na amplitudes and slowed current inactivation. Stimulation by TEL of I_Na in HL‐1 cells did not simply increase current magnitude but altered current kinetics, thereby suggesting state‐dependent activation. Telmisartan may have greater affinity to the open/inactivated state than to the resting state residing in Na_V channels. Collectively, TEL‐mediated stimulation of I_Na and inhibition of I_K(erg) could be an important ionic mechanism underlying the increased cell excitability of HL‐1 cells; these actions, however, cannot be entirely explained by its blockade of AT₁ receptor.     

微弧氧化电压处理钛表面后对钛瓷结合强度的影响

目的：观察钛试样在微弧氧化处理过程中，电源电压不同，形成的氧化膜对钛瓷结合强度的影响。方法：电解液由去离子水和Na2SiO3溶液组成，占空比和频率为0．04、500Hz，时间3min，电压分别为Ⅰ组300V；Ⅱ组350V；Ⅲ组400V，分别对钛试样表面进行处理，扫描电镜（SEM）观察膜表面形貌；对不同组别试件进行瓷粉烧结，再采用三点弯曲试验测量钛与瓷的结合强度。结果：随电压的升高，钛试件表面形貌变化较大，微孔直径增大，微孔的数量明显减少，表面变得粗糙不平，氧化膜的厚度也随之增加，从5μm增加到10μm；钛与瓷的结合强度随电压增大逐渐降低，但微弧氧化组的结合强度明显高于未行微弧氧化组（P〈0.01）。结论：钛在烤瓷前经微弧氧化处理有利于钛与瓷的结合，且微弧氧化过程中不同处理电压对钛瓷结合强度有影响。     

皮瓣修复腕部高压电烧伤创面的手术时机选择

〔摘 要〕 目的：分析对腕部高压电烧伤患者创面进行手术修复的过程中选取不同手术时机对于患者治疗效果的影响。 方法：选取2018年11月至2019年11月期间娄底市第一人民医院烧伤整形外科收治的100例腕部高压电烧伤患者为研究对象, 依据手术时机的不同将其分为对照组和观察组,各 50 例。对照组患者经其他治疗后进行皮瓣修复治疗,观察组患者在受伤 当日即进行皮瓣修复治疗,对两组患者临床治疗效果进行比较。结果：观察组患者手术用时、皮瓣移植面积以及住院用时 情况均优于对照组,差异具有统计学意义（P ＜ 0.05）;在清创后面积方面,组间比较,差异无统计学意义（P ＞ 0.05）。 在患者恢复情况方面,观察组患者在桡神经、尺神经、正中神经、中腕部屈曲能力以及屈指肌腱功能等方面的恢复效果均 优于对照组,差异具有统计学意义（P ＜ 0.05）。结论：在对腕部高压电烧伤患者进行皮瓣修复的过程中,尽早开展手术, 对于患者手术指标与功能恢复的优化具有一定价值。