Anoxic depolarization of rat hippocampal slices is prevented by thiopental but not by propofol or isoflurane

Background. There is strong evidence to suggest that anoxicdepolarization (AD) is an important factor in hypoxia/ischaemia-inducedneural damage. Treatments that prevent the occurrence of ADmay be useful in providing neuronal protection against hypoxia.The current study was designed to determine whether generalanaesthetics which have been suggested to ‘induce prophylaxis’against hypoxia can attenuate the incidence of AD. Methods. The effects of anoxia (3 min) on evoked extracellularlyrecorded field potentials of CA1 neurons in rat hippocampalslices were assessed in the absence and presence of the i.v.general anaesthetics thiopental and propofol and the volatileanaesthetic isoflurane. Results. In the absence of anaesthetics, AD occurred in 81%of the preparations tested. Thiopental (2x10^–4 M) significantlyreduced the incidence of AD (16%, P=0.0006). In comparison,propofol (2x10^–4 M) and isoflurane (1.5 vol%) were ineffective(69% and 60%, respectively). Furthermore, in the presence ofthiopental, the population spike amplitude recovered with andwithout AD (90% and 94% of pre-anoxic value, respectively) following3 min anoxia. Conclusion. The prophylactic effect of thiopental against hypoxiamight be induced, in part, by preventing the generation of AD.     

Stiffness measurement of the neocallus with the Fraktometer FM 100<Superscript>®</Superscript>

Introduction: The assessment of fracture healing is subjective, and neither radiology nor manual examination allows a reliable determination of bone healing. Fracture healing control in the treatment of tibia shaft fracture with external fixator by a stiffness measurement system (Fraktometer FM 100^®) is known from clinical studies. The purpose of this study was to follow stiffness control at external fixator in healing of callotasis with the stiffness measurement system. Materials and methods: From 1994 to 1997 stiffness measurements with the described system (Fraktometer FM 100) were performed in the BG-Clinic Ludwigshafen to assess the healing course in 11 cases of callotasis at lower limb. Results: In ten cases, regular healing could be followed by signal decrease; in one case, a persistent signal without tendency to decrease was able to reveal callotasis failure at an early point of time. The investigation could also show the importance of bending stiffness control. One case of late axis deformation after fixator removal occurred because of disregarding delayed bending signal decrease. Conclusion: Measurements of the external fixator’s stiffness after callotasis can provide useful additional information for further treatment strategy.     

Effects of stellate ganglion block on cerebral haemodynamics as assessed by transcranial Doppler ultrasonography

Background. Stellate ganglion block (SGB) causes vasodilatationin the skin of the head and neck because of regional sympatheticblock. Its effects on cerebral haemodynamics, in health or indisease, are not clear. We evaluated the effects of SGB on ipsilateralmiddle cerebral artery flow velocity (MCAFV), estimated cerebralperfusion pressure (eCPP), zero flow pressure (ZFP), carbondioxide reactivity (CO₂R) and cerebral autoregulation usingtranscranial Doppler ultrasonography (TCD). Methods. Twenty male patients, with pre-existing brachial plexusinjury, and undergoing SGB for the treatment of complex regionalpain syndrome of the upper limb, were studied. For SGB, 10 mlof plain lidocaine 2% was used and the onset of block was confirmedby presence of ipsilateral Horner's syndrome. The MCAFV, eCPP,ZFP, CO₂R, and cerebral autoregulation were assessed beforeand after SGB using established TCD methods. The changes inthese variables were analysed using Wilcoxon's signed rank test. Results. The block caused a significant decrease in MCAFV frommedian (inter-quartile range) value of 61 (53, 67) to 55 (46,60) cm s^–1, a significant increase in eCPP from 59 (51,67) to 70 (60, 78) mm Hg, and a significant decrease in ZFPfrom 32 (26, 39) to 25 (16, 30) mm Hg. There were no significantchanges in CO₂R or cerebral autoregulation. Conclusion. The increase in eCPP, decrease in ZFP, and no changesin CO₂R or cerebral autoregulation suggest that the SGB decreasescerebral vascular tone without affecting the capacity of thevessels to autoregulate. These effects may be of therapeuticadvantage in relieving cerebral vasospasm in certain clinicalsettings.     

Measurement of foot placement and its variability with inertial sensors

Gait parameters such as stride length, width, and period, as well as their respective variabilities, are widely used as indicators of mobility and walking function. Foot placement and its variability have thus been applied in areas such as aging, fall risk, spinal cord injury, diabetic neuropathy, and neurological conditions. But a drawback is that these measures are presently best obtained with specialized laboratory equipment such as motion capture systems and instrumented walkways, which may not be available in many clinics and certainly not during daily activities. One alternative is to fix inertial measurement units (IMUs) to the feet or body to gather motion data. However, few existing methods measure foot placement directly, due to drift associated with inertial data. We developed a method to measure stride-to-stride foot placement in unconstrained environments, and tested whether it can accurately quantify gait parameters over long walking distances. The method uses ground contact conditions to correct for drift, and state estimation algorithms to improve estimation of angular orientation. We tested the method with healthy adults walking over-ground, averaging 93 steps per trial, using a mobile motion capture system to provide reference data. We found IMU estimates of mean stride length and duration within 1% of motion capture, and standard deviations of length and width within 4% of motion capture. Step width cannot be directly estimated by IMUs, although lateral stride variability can. Inertial sensors measure walks over arbitrary distances, yielding estimates with good statistical confidence. Gait can thus be measured in a variety of environments, and even applied to long-term monitoring of everyday walking.     

高强度磁脉冲刺激在临床应用的研究进展

无创性磁刺激技术在中枢神经功能检测和神经肌肉功能恢复的应用是医学工程研究的一个新热点。文章从理论上对磁刺激的发生发展、物理原理、特性、磁刺激与标准电刺激的差别、外周磁刺激技术的多信道磁刺激对电刺激模拟等最新的发展,以及临床上磁刺激在神经肌肉功能恢复的作用等做了全面介绍。     

乳腺钼靶片计算机光密度测定的临床应用研究

目的：利用计算机对乳腺钼靶片上病灶中心及病灶周围影像光密度的测定，来探索良、恶性乳腺病变之间以及各种病变病灶中心与病灶周围影像的密度差异：探讨病理基础和临床意义。材料和方法：随机选取１００例临床可扪及乳腺＂肿块＂的女性病人，进行乳腺钼靶Ｘ线检查，将检出病变的１０２张钼靶片进行计算机处理后，对病灶中心及病灶周围组织影像的光密度进行测定。所有病例除炎性病变外均取得病理结果。结果：１．良性病变的病灶中心密度与病灶周围密度无显著差异（Ｐ＞０．５），良性肿块（指纤维腺瘤和囊肿）的病灶中心与病灶周围密度间仅提示一种可能存在显著差异的趋势（０．１＞Ｐ＞０．０５）；２．乳腺癌病灶中心与病灶周围密度之间存在非常显著的差异（Ｐ＜０．００１）；３．良、恶性肿瘤病灶中心密度之间存在较显著差异（Ｐ＜０．０５）。结论：本研究的结果有助于乳腺良、恶性病变的鉴别诊断和提高早期乳腺癌的检出率。     

Accuracy of accelerated cine MR imaging at 3 Tesla in longitudinal follow-up of cardiac function

The ability of fast, parallel-imaging-based cine magnetic resonance (MR) to monitor global cardiac function in longitudinal exams at 3 Tesla was evaluated. Seventeen patients with chronic cardiac disease underwent serial cine MR imaging exams (n = 3) at 3 Tesla. Data were acquired in short-axis orientation using cine steady-state free precession (SSFP) with a spatial resolution of 2.5 x 1.9 mm(2) at 45 ms temporal resolution. Multislice imaging (three slices/breath-hold) was performed using TSENSE acceleration (R = 3) and standard single-slice cine (non-TSENSE) was performed at identical locations in consecutive breath-holds. End-diastolic volume (EDV), end-systolic volume (ESV), ejection fraction (EF) and myocardial mass (MM) of both cine approaches were compared for individual time-points as well as for longitudinal comparison. TSENSE-cine did not show significant differences for EDV (2.6 ml; P = 0.79), ESV (2.2 ml; P = 0.81), EF (-0.3%; P = 0.95) and MM (2.4 g; P = 0.72) in comparison with non-TSENSE. Longitudinal ANOVA analysis did not reveal significant differences for any parameter, neither for non-TSENSE data (all P > 0.7) nor for TSENSE data (all P > 0.9). Multifactorial ANOVA showed non-significant differences (all P > 0.7) at comparable data variances. Data acquisition was significantly shortened using TSENSE. Threefold accelerated multislice cine at 3 Tesla allows accurate assessment of volumetric LV data and accurate longitudinal monitoring of global LV function at a substantially shorter overall examination time.     

Giant arachnoid granulation in a patient with benign intracranial hypertension

We report magnetic resonance (MR), computed tomography (CT) and angiographic imaging of an unusual giant arachnoid granulation in the superior sagittal sinus in a man with headache and vertigo. Intrasinus pressure measurements revealed a significant pressure gradient across the lesion. MR imaging is useful to identify giant arachnoid granulation and dural sinus thrombosis, whereas dural sinus pressure measurement in certain cases of giant arachnoid granulations can be used to evaluate the lesion as the cause of the patient's symptoms.     

以室间质量评价的已知值计划提高血清肌酐测定的准确度

目的：通过参加美国病理家协会的校正验证／线性对比研究（CAP—LN），验证血清肌酐在可报告范围内结果的准确性，评价分析系统的校正是否有效，为肌酐测量的质量改进提供依据。方法：有目的性地进行3次仪器样本量参数的修改，每修改一次便重新测定2005LN24-A研究的样本材料（过去分析后的存留样本），比较3次测定结果线性回归图的统计数据，以确定最佳的样本参数，并参加随后的LN24-B比对研究以验证效果。结果：LN24-B比对研究的结果显示．肌酐的线性范围评价结果为线性1（Linear 1），校正验证结果为验证1（Verified 1），说明分析检测系统的校正有效。结论：通过LN24比对研究，可评价肌酐测定值与NIST靶值间在可报告范围内差异，实验室可根据研究结果，分析误差产生的原因，从而采取有效措施提高准确度。     

免疫透射和免疫散射比浊法测定血清免疫球蛋白及补体的比较

目的：比较免疫透射和免疫散射比浊法测定免疫球蛋白和补体时的准确性、精密度、偏离度及测定范围。方法：采用贝克曼LX-20与DELTA特定蛋白分析仪，分别以免疫透射和免疫散射比浊法，对同一临床标本测定血清中免疫球蛋白（IgG、IgA、IgM）和补体（C3、C4）的含量。结果：两种仪器测定IgG、IgA、IgM、C3、CA准确性、精密度均良好。两法各浓度值测定结果的预期偏差均在可接受范围。结论：贝克曼LX-20应用免疫透射比浊法与DELTA特定蛋白分析仪应用免疫散射比浊法测定免疫球蛋白和补体准确性、精密度均比较好，且散射比浊法优于透射比浊法。