化学实验进行开放式教学的研究

通过与传统的化学实验教学模式的比较，详述了开放式教学模式的特点，并且针对实施过程中所遇到的问题提出了详尽的解决方案。     

Separation of temperature sensitive and temperature insensitive components of the postsynaptic potentials in the frog motoneurons

Intracellular measurements were made in the in situ spinal cord of the frog at temperatures below 5 degrees C. Responses to volleys in the sciatic nerve, in the descending fibres and in the motor axons were studied. About 30% of the motoneurons responded to sciatic volleys with 1-3 ms segmental latency, which was short enough to assume electrotonic mediation of these responses. Another group of motoneurons responded with 6-8 ms latency, i.e. with the expected delay at chemical synapses at low temperature. Latency distribution of the sciatic-evoked postsynaptic potentials was clearly bimodal in contrast with that found at higher temperatures. Postsynaptic discharges occurred with rather long latency and they were attributed to chemically-mediated excitation. Some of the postsynaptic potentials to descending volleys also occurred with quite short latency, indicating possible electrotonic transmission from supraspinal centres to motoneurons. Latency distribution of the action potentials evoked from the motor axons was bimodal, corresponding to the different, i.e. antidromic and recurrent facilitatory, mechanism of these spikes. Calculated Q10 ratios for the sciatic-evoked reflex discharges and the afferent fibre volleys were about 2.3 and 1.8, respectively. We concluded that cooling helps to separate postsynaptic potentials according to their electrotonic and chemical mediation and that electrotonic excitation does not seem to have a primary role in the generation of postsynaptic discharges initiated by dorsal root volleys in the frog.     

Dorsal bundle extinction effect: Motivation or attention?

Male albino Wistar rats were injected bilaterally with 4 micrograms of 6-hydroxydopamine into the dorsal noradrenergic bundle to deplete forebrain noradrenaline to less than 5% of control values. Acquisition learning of a fixed interval schedule or a continuously reinforced schedule was not altered but resistance to extinction was seen after food reinforced training on either schedule but not after water reinforced training. A possible increase in food motivation was tested by the use of preloading with free food prior to a fixed interval session but both control and lesioned rats reacted similarly to this manipulation thus appearing to exclude an increase in food motivation. An attentional explanation is proposed and tested by the demonstration that resistance to extinction does not occur after a partially (variable ratio 4), as opposed to a continuously, reinforced schedule. Further evidence in favour of an attentional mechanism comes from the finding that on both a fixed interval and a continuously reinforced schedule the lesion has to be present during the acquisition phase to result in subsequent resistance to extinction. Intact animals trained on either schedule and subsequently subjected to the lesion failed to show an increased resistance to extinction.     

CT三维容积重建在颌骨疾病诊治中的应用

目的　评价CT三维容积重建在颌面骨病变诊治中的应用价值。方法　用MX 80 0 0双排螺旋CT机的 4D Angio软件处理容积数据得到高度仿真的三维CT ,可直观清晰地显示颌骨病变的部位、范围、程度及其与邻近结构的关系 ,有利临床作出准确诊断 ,正确选择手术方法和确定手术进路。结果　CT三维容积重建可以直观地显示颌合骨的复杂结构及其病变的整体形态 ,对骨折复位和病变彻底切除起到重要作用。结论　与常规断面CT以及三维表面遮蔽 (SSD)重建相比 ,MX 80 0 0的 4D Angio软件 (相当于volumerender ing软件 ,即VR)做出的CT三维容积重建 (VR)更有立体感 ,更能展现解剖结构的自然形态 ,而且其为容积数据的全息处理 ,可显示骨质内部结构 ,因而能为临床提供更直观 ,详实的形态学资料 ,便于确诊并可优化手术方案和最大限度减少手术创伤 ,有利于功能和形态的更好恢复     

桌面虚拟现实技术在医学多媒体课件中的设计与应用

介绍了桌面虚拟现实技术在课件制作中的设计思路及实现方法。指出将虚拟现实技术与课件教学内容的知识点相整合,可强化课件的学习自主性和知识交互性,从而提高学习效率和教学质量。     

Effects of TRPV1 activation on synaptic excitation in the dentate gyrus of a mouse model of temporal lobe epilepsy

Temporal lobe epilepsy (TLE) is a condition characterized by an imbalance between excitation and inhibition in the temporal lobe. Hallmarks of this change are axon sprouting and accompanying synaptic reorganization in the temporal lobe. Synthetic and endogenous cannabinoids have variable therapeutic potential in treating intractable temporal lobe epilepsy, in part because cannabinoid ligands can bind multiple receptor types. This study utilized in vitro electrophysiological methods to examine the effect of transient receptor potential vanilloid type 1 (TRPV1) activation in dentate gyrus granule cells in a murine model of TLE. Capsaicin, a selective TRPV1 agonist had no measurable effect on overall synaptic input to granule cells in control animals, but significantly enhanced spontaneous and miniature EPSC frequency in mice with TLE. Exogenous application of anandamide, an endogenous cannabinoid that acts at both TRPV1 and cannabinoid type 1 receptors (CB1R), also enhanced glutamate release in the presence of a CB1R antagonist. Anandamide reduced the EPSC frequency when TRPV1 were blocked with capsazepine. Western blot analysis of TRPV1 receptor indicated protein expression was significantly greater in the dentate gyrus of mice with TLE compared with control mice. This study indicates that a prominent cannabinoid agonist can increase excitatory circuit activity in the synaptically reorganized dentate gyrus of mice with TLE by activating TRPV1 receptors, and suggests caution in designing anticonvulsant therapy based on modulating the endocannabinoid system.     

Relationship Between the Contrast Effects of Raw Data Projection Images from Three-Dimensional Digital Subtraction Angiography and the Optimal Volume Rendering Parameters

Volume rendering (VR) is a technique commonly used for the reconstruction of three-dimensional (3D) digital subtraction angiography (DSA) images, and the rendering parameters greatly affect the characteristics of the 3D image. This study aimed to test whether the optimal VR parameters for 3D DSA could be estimated from the contrast effects in rotational two-dimensional (2D) DSA images acquired using 3D DSA. Simulated blood vessels filled with various concentrations of contrast medium were scanned, and the 3D DSA data sets were reconstructed. The syngo AX vessel analysis software that was able to analyze 3D DSA VR image was used for objective measures. Raw data projection images of the 3D DSA data sets in which the mean diameter was calculated as a true value by the software at nine different thresholds for vessel segmentation were selected. In each image set, five images of all 133 rotational 2D DSA images were selected, and the contrast-enhanced area was extracted using a region-growing algorithm. Mean values and standard deviations of each contrast-enhanced area were calculated, and as the thresholds for vessel segmentation of the software increased by 500 every time, significant differences were observed in the mean values (P < 0.01). This optimal threshold can be applied to the window settings of the VR technique. Therefore, the optimal VR parameters for 3D DSA may be determined by analyzing the contrast effects of the raw data projection images, and user-dependent over- and underestimations of 3D DSA VR images also may be prevented.     

Virtual Reality Rehabilitation With Functional Electrical Stimulation Improves Upper Extremity Function in Patients With Chronic Stroke: A Pilot Randomized Controlled Study

Objective

To compare virtual reality (VR) combined with functional electrical stimulation (FES) with cyclic FES for improving upper extremity function and health-related quality of life in patients with chronic stroke.