MC-Ⅲ型低频脉冲强磁场发生仪的研制

介绍了我们研制的强脉冲磁场发生仪。该发生仪可输出磁感应强度为 0 .1～ 2 .5 T,周期可调的脉冲磁场。使用表明 ,该仪器操作方便、性能可靠 ,可长时间稳定运行 ,已在磁场生物效应的科学实验中得到广泛应用     

胶原的医学应用及其发展前景

本文概括地阐明了胶原的主要结构特征，对胶原的主要性质，诸如理化性质、物理一机械性能、医用性能等进行了讨论。在此基础上，较为系统地介绍了胶原在医学领域中的应用。胶原可以用于制造天然真皮替代物、人工皮肤、可注射胶原、可降解胶原缝线、止血海绵、组织引导材料及用于骨组织工程中的“I型胶原-X”植入材料等。最后展望了胶原在医学领域中的应用及其发展前景。     

应力、极低频脉冲电磁场与成骨细胞

电磁与机械环境能够影响成骨细胞的生长与分化,关于其作用机理的研究每年都有大量的相关报道,主要针对细胞内的钙过程综述了极低频电磁场与机械因子对成骨细胞的作用途径,并对它们之间的异同进行了比较。     

Micronuclei formation in somatic cells of mice exposed to 50-Hz electric fields

Male Swiss mice are tested under uniform 50-Hz electric field intensities of 100, 170, 220, and 290 kV/m. These values on the basis of equal induced current density are equivalent to the case of a human exposed to field intensities of nearly 8, 14, 18, and 24 kV/m, respectively. The latter values may be found beneath or in the vicinity of extra-high-voltage power lines whose voltages range from 220 to 765 kV. The cytogenetic effect of extremely low-frequency (ELF) electric fields, as expressed by micronuclei formation, is assessed. Mice are exposed for 24 hr, and samples are taken 48, 72, and 96 hr from the beginning of exposure. Sham-exposed mice served as controls. The number of micronucleated polychromatic erythrocytes (PCE) in exposed animals are significantly higher than those of the control. The increase in micronucleated PCE was significantly dose dependent at all times. Samples taken 96 hr after exposure show a decrease in percentages of micronucleated PCE, which may be taken as an indication of recovery.     

刺五加对冠心病心绞痛左心室舒张功能的影响

目的: 观察刺五加对冠心病心绞痛左室舒张功能的影响。方法:应用脉冲多普勒超声心动图对冠心病心绞痛患者静脉输入刺五加前后测定左室舒张功能。结果:用药后舒张早期充盈速度增加,血流加速度和房缩期充盈速度下降,左室等容舒张期缩短。结论:刺五加能明显改善冠心病心绞痛的左室舒张功能     

Model-based technique for the measurement of skin thickness in mammography

A model-based method is proposed for the measurement of breast skin thickness from digitised mammograms that takes into account both the geometric and radiographic properties of the skin region. The method initially identifies a salient feature that discriminates the skin from the other anatomical structures of the breast. Its identification is based on a multi-scale grey-level gradient estimation, using a wavelet decomposition of the image. The spatial distribution of this feature is organised as a graph, with each of its nodes associated with a binary set of interpretation labels. A Markov randomfield is defined on the set of labels, and the best graph labelling is finally determined with a maximum a posteriori (MAP) probability criterion. The method was applied on 11 mammograms with improved contrast characteristics at the breast periphery, obtained by an exposure equalisation technique during image acquisition. The validation of the approach was performed by calculating the root mean square (RMS) error between the detected skin thickness and manual measurements performed on each of the films. The resulting error values ranged from 0.1 mm to 0.2 mm for normal cases and reached a maximum of 0.5 mm in pathological cases with advanced skin thickening.     

Frontal lobe lesions in man cause difficulties in suppressing reflexive glances and in generating goal-directed saccades

Summary The frontal eye field (FEF) and superior colliculus (SC) are thought to form two parallel systems for generating saccadic eye movements. The SC is thought classically to mediate reflex-like orienting movements. Thus it can be hypothesized that the FEF exerts a higher level control on a visual grasp reflex. To test this hypothesis we have studied the saccades of patients who have had discrete unilateral removals of frontal lobe tissue for the relief of intractable epilepsy. The responses of these patients were compared to those of normal subjects and patients with unilateral temporal lobe removals. Two tasks were used. In the first task the subject was instructed to look in the direction of a visual cue that appeared unexpectedly 12° to the left or right of a central fixation point (FP), in order to identify a patterned target that appeared 200 ms or more later. In the second anti-saccade task the subject was required to look not at the location of the cue but in the opposite direction, an equal distance from FP where after 200 ms or more the patterned target appeared. Three major observations have emerged from the present study. (a) Most frontal patients, with lesions involving both the dorsolateral and mesial cortex had long term difficulties in suppressing disallowed glances to visual stimuli that suddenly appeared in peripheral vision. (b) In such patients, saccades that were eventually directed away from the cue and towards the target were nearly always triggered by the appearance of the target itself irrespective of whether or not the anti-saccade was preceded by a disallowed glance. Those eye movements away from the cue were only rarely generated spontaneously across the blank screen during the cue-target time interval. (c) The latency of these visually-triggered saccades was very short (80–140 ms) compared to that of the correct saccades (170–200 ms) to the cue when the cue and target were on the same side, thereby suggesting that the structures removed in these patients normally trigger saccades after considerable computations have already been performed. The results support the view that the frontal lobes, particularly the dorsolateral region which contains the FEF and possibly the supplementary motor area contribute to the generation of complex saccadic eye-movement behaviour. More specifically, they appear to aid in suppressing unwanted reflex-like oculomotor activity and in triggering the appropriate volitional movements when the goal for the movement is known but not yet visible.     

Maps of Surface Distributions of Electrical Activity in Spectrally Derived Receptive Fields of the Rat's Somatosensory Cortex

This study describes the results of experiments motivated by an attempt to understand spectral processing in the cerebral cortex (DeValois and DeValois, 1988; Pribram, 1971, 1991). This level of inquiry concerns processing within a restricted cortical area rather than that by which spatially separate circuits become synchronized during certain behavioral and experiential processes. We recorded neural responses for 55 locations in the somatosensory (barrel) cortex of the rat to various combinations of spatial frequency (texture) and temporal frequency stimulation of their vibrissae. The recordings obtained from single and multi-unit bursts of spikes were mapped as surface distributions of local dendritic potentials. The distributions showed a variety of patterns that are asymmetric with respect to the spatial and temporal parameters of stimulation, and were, therefore, not simply reflecting whisker flick rate. Next, a simulation of our results showed that these surface distributions of local dendritic potentials can be described by Gabor-like functions much as in the visual system. The results provide support for a model of distributed cortical processing that imposes a physiologically derived frame (the limited extent of a dendritic patch) and an anatomically derived (axonal) sampling of the distributed process. This combination provides a complex Gabor wavelet that encodes phase, which is necessary to processing such details as edges and texture in a scene. The synchronization across cortical areas that make the Gabor wavelet processes within restricted cortical areas available to one another (the binding problem) proceed at a 'higher order' level of integration. Both levels of distributed processing accomplish computation in the conjoint spacetime and spectral domain. This revised version was published online in July 2006 with corrections to the Cover Date.     

900 MHz电磁辐射对淋巴细胞作用的显微激光共焦拉曼光谱研究

目的:探讨900 MHz电磁波对淋巴细胞的影响.方法:利用显微激光共焦拉曼光谱技术获得功率密度为5mW/cm2的900 MHz电磁波照射不同时间的淋巴细胞的拉曼光谱.结果:照射20 min后,部分淋巴细胞拉曼光谱出现了微小变化;照射40 min后,包含类胡萝卜素信息的细胞核拉曼光谱出现明显变化,细胞核的拉曼光谱的一些谱带也发生了变化;照射60 min后,淋巴细胞拉曼光谱位于787 cm-1的谱线移动了8 cm-1,显示细胞核受到电磁辐射后产生明显的损伤.结论:长时间处于5 mW/cm2电磁波作用下(≥40min),淋巴细胞出现损伤,损伤主要表现在蛋白构象变化和DNA的碱基受到损伤,从而影响其功能.