Biomechanical assessment with electromyography of post-stroke ankle plantar flexor spasticity

Spasticity has been defined as a motor disorder characterized by a velocity-dependent increase in tonic stretch reflex (muscle tone). Muscle tone consists of mechanical-elastic characteristics, reflex muscle contraction and other elements. The aims of this study were to determine whether to assess spasticity quantitatively, and to characterize biomechanical and electromyographic spasticity assessment parameters. These assessment parameters were described by investigating the correlation between clinical measures and the response to passive sinusoidal movement with consecutive velocity increments. Twenty post-stroke hemiplegic patients and twenty normal healthy volunteers were included in the study. Five consecutive sinusoidal passive movements of the ankle were performed at specific velocities (60, 120, 180, and 240 degrees/ sec). We recorded the peak torque, work, and threshold angle using a computerized isokinetic dynamometer, and simultaneously measured the rectified integrated electromyographic activity. We compared these parameters both between groups and between different velocities. The peak torque, threshold angle, work, and rectified integrated electromyographic activity were significantly higher in the post-stroke spastic group at all angular velocities than in the normal control group. The threshold angle and integrated electromyographic activity increased significantly and linearly as angular velocity increased, but the peak torque and work were not increased in the post-stroke spastic group. Peak torque, work, and threshold angle were significantly correlated to the Modified Ashworth scale, but the integrated electromyographic activity was not. The biomechanical and electromyographic approach may be useful to quantitatively assess spasticity. However, it may also be very important to consider the different characteristics of each biomechanical parameter.     

Investigation of the involvement of opioid receptors in the action of anticonvulsants

This study investigates the possible involvement of opioid receptors in the action of a variety of anticonvulsant agents. The opioid antagonist naloxone (0.3, 1 mg/kg IP) and the selective -opioid antagonist cyprodime (3 mg/kg IP) significantly inhibited the increase in electroshock seizure threshold induced by phenytoin (3 mg/kg IP) in mice. The anticonvulsant effects of ethanol (1 g/kg IP) were also significantly antagonised by naloxone (1 mg/kg IP) but not by a 0.3 mg/kg IP dose or by cyprodime (3 mg/kg IP). The results with naloxone were confirmed using higher doses of phenytoin (10 mg/kg IP) and ethanol (1.5 g/kg IP). In contrast to the above findings, naloxone (0.3, 1 mg/kg IP) had no effect on the increase in seizure threshold induced by sodium valproate (200 mg/kg IP) or dizocilpine (MK801, 0.5 mg/kg IP) and paradoxically potentiated the increase in seizure threshold produced by phenobarbitone (15 mg/kg IP); carbamazepine (10 mg/kg IP) and the benzodiazepine agonist loprazolam (1 mg/kg IP), clearly differentiating these compounds from phenytoin and ethanol. These findings suggest that the anticonvulsant effects of phenytoin and ethanol (as assessed by their ability to prevent tonic hindlimb extension in the mouse electroshock model) may be mediated, at least in part, by the release of endogenous opioids and subsequent activation of opioid receptors (, in the case of phenytoin, but non-, in the case of ethanol) although direct activity at opioid receptors cannot be precluded.     

中脑导水管周围灰质内注射抗强啡肽血清对神经降压素镇痛作用的影响

目的：探讨大鼠中脑导水管周围灰质（PAG）内内源性强啡肽对神经降压素（NT）镇痛作用的影响。方法：以钾离子透入法引起大鼠甩尾反应的电流强度（mA)为痛行为反应的指标,观察向PAG内注入NT,抗神经降压素血清和抗强啡肽A1－13血清对动物痛阈的影响。结果：PAG内注入NT后,大鼠痛阈明显升高;注入抗神经降压素血清后,大鼠痛阈则明显降低,而注入抗强啡肽血清后,对NT的镇痛效应无显著影响,结论：PAG内NT在痛觉调制中发挥着重要的作用,且其作用不依赖于PAG内的内源性强啡肽。     

噪声、照明、温度、湿度对听觉的复合作用

观察舰艇舱室环境噪声、照明、温度、湿度４种物理因素联合作用对暂时性听阈偏移的影响。方法：受试者分析在（１）７５ｄＢＡ、２００ｌｘ、２５℃、６５％ＲＨ;（２）７５ｄＢＡ,６１ｘ、３５℃、８５％ＲＨ;（３）８５ｄＢＡ、８０ｌｘ、３５℃;（）ＤｂＡ、８０ｌｘ、３０℃、７５％ＲＨ;（５）９０ｄＢＡ、１８０ｌｘ、２７℃、６０％ＲＨ;（６）９６ｄＢＡ、２００ｌｘ、２５℃、６５％ＲＨ;（５）９５ｄＢＡ、６ｌｘ、     

半导体激光穴位照射的镇痛作用及其机制初探

目的　探讨半导体激光穴位照射镇痛效应及其镇痛的机制。方法　大鼠随机分成照射组、模拟照射组和纳洛酮预处理组。采用半导体激光照射大鼠“足三里”穴位 ,用电刺激鼠尾 -嘶叫法测定激光照射前后的痛阈。结果　照射后大鼠的痛阈明显提高 ,这种镇痛作用可被纳洛酮预处理所翻转。结论　半导体激光穴位照射产生镇痛效应机制可能与激光照射促进内源性阿片物质释放有关。     

Effect of adeno-tonsilectomy on hearing threshold and middle ear pressure

Out of 50 children (100 ears) undergoing adeno-tonsillectomy, 34 ears had hearing threshold 20–50 dB (20dB is normal) and 32 ears showed negative middle ear pressure of 100 to 400 mmH₂O (100 mmH₂O is normal). Post-operatively only 7 ears had hearing threshold of 20–30 dB and negative middle ear pressure of 100 to 200 mmH₂O. Thus adenoidectomy improves eustachian tube functions.     

Laser energy threshold for thermal vascular injury in a port-wine stain skin model

Monte Carlo simulation of laser energy deposition in a port-wine stain (PWS) skin model and numerical solution of the thermal diffusion equation have been used to calculate threshold energies for thermal injury of PWS blood vessels for different vessel sizes and laser pulse durations. It has been assumed that an average vessel temperature rise of 65 C causes thermal injury to the blood vessel. The result is that for a certain combination of wavelength, pulse duration and incident energy density, only a limited range of blood vessel sizes can be injured optimally. Higher energy densities are required to injure smaller vessels with the same pulse duration, spot size and wavelength. This gives support to the mechanisms of selective photothermolysis suggested previously by Anderson and Parrish, although their model was based on the cooling behaviour of instantaneously heated vessels. The authors hypothesize that different laser parameter settings that match the individual PWS vessel anatomy during treatment will be used in the future, instead of many treatments with the same laser parameters. This could lead to less treatment sessions and to an improved predictability of clinical results.     

Transient decrease in sound tolerance levels following hearing deprivation in normal-hearing subjects

ObjectiveTo determine the circadian influence on sound sensitivity produced by temporal hearing deprivation in healthy normal human subjects.DesignParticipants underwent bilateral earplugging before completion of anthropometry, the author's developed questionnaire, the Hamilton Anxiety and Depression Inventory, pure tone audiometry (PTA), stapedial reflex thresholds (SRT), distortion products otoacoustic emissions input/output (DPOAE-I/O), and uncomfortable loudness levels (ULLs). Afterward, the participants were randomly divided into group A, starting at 8:00 a.m. and finishing at 8:00 p.m., and group B, starting at 4:00 p.m. and ending at 4:00 a.m. Serum cortisol levels and audiological test results were obtained at the beginning and end of the session and 24-h free urinary cortisol levels were measured.Study sampleThirty healthy volunteers.ResultsPTA was 2.68 and 3.33 dB HL in groups A and B, respectively, with no statistical difference between them. ULLs were significantly lower in group A compared to group B, with an average of 8.1 dB SPL in group A and 3.3 dB SPL in group B (p < 0.0001). A SRT shift was observed in group A, with no difference in group B, and a night shift in DPOAE-I/O in group B.ConclusionsReduced loudness tolerance is demonstrated during daytime hearing deprivation in contrast to nighttime; this may be due to increased central gain in the awake cortex.     

Experimental analysis of the human perception threshold of a DC electric field

To study the biological effects of extremely low frequency (ELF) electric fields, a fundamental study is conducted of the human perception threshold of an electric field. The perception threshold is measured with human subjects, and the results are analysed. It is clear that field perception is based on the movement of hair and not on other sensations. Variance in the perception threshold and its causes are investigated. The perception threshold decreases by almost 30% as the relative humidity increases from 50 to 90%. The perception threshold is also dependent on the physical condition (length and density) of the hair and the psychological condition (degree of awareness) of the subject. The dependence on these is much smaller than that on relative humidity. The cause of the gender difference in the threshold is ascribed to the difference in the physical condition of the hair. Through this study, some factors to be taken into account for the safety standard are made clear.     

心房按需起搏时心内电图的形态与起搏参数的关系

目的： 观察心房按需起搏（ＡＡＩ）时心内电图的形态与起搏阈值等参数的关系。　方法：对３６ 例ＡＡＩ起搏时记录的心内电图的Ａ 波形态、振幅、Ａ－Ｖ段上抬幅度进行详细测定,并与起搏阈值、心肌阻抗等参数进行相关分析。　结果：Ａ波形态、振幅与起搏阈值、心肌阻抗均无显著相关（Ｐ＞ ０．０５）,而Ａ－Ｖ 段上抬的幅度与起搏阈值呈明显负相关（ｒ＝ － ０．５４８ ６, Ｐ＜ ０．０５）。Ａ－Ｖ段高抬组的起搏阈值（０．６８±０．１７）Ｖ,显著低于Ａ－Ｖ段低抬组的（１．１±０．２４）Ｖ （Ｐ＜ ０．０１）。　结论：心内电图Ａ－Ｖ段上抬的足够幅度（＞ ０．３ ｍ Ｖ）可作为ＡＡＩ起搏时的一个重要技术指标,对避免电极脱位、保证较低的起搏阈值水平均具重要的临床意义。