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Dominant Frequency Uncertainty Analysis of EEG α Activity in Pilots with Transient Ischemic Attacks

Chuandai ZHOU ; Dongxu HAN ; Yuehong LIU ; Yijuan ZHAI ; Yansong LI

Space Medicine & Medical Engineering.1999;12(2):84-87.

Objective To study the characteristics of EEG after tramsient ischemic attack and to offer reference for screening procedure of aircrew and astronaut selection. Method The dominant frequency uncertainty of alpha band EEG in 12 pilots(males; age 30±5) with transient ischemic episodes in middle cerebral artery(MCA) territories and in 20 normal healthy pilots was analyzed with frequency-fluctuation analysis. Result The dominant probability of the main frequency coinciding with sites affected by transient ischaemic attack(TIA) in patient pilots was higher than that in healthy pilots (P<0.01),and the dominant probability ratio logarithmic index I≥0 in all patient pilots with normal EEG, but I<0 in all healthy pilots. It was also found that not only I≥0, but the second component shifted to lower frequency(8 Hz) in patients with slight focal EEG alterations,i.e. slowing of frequency. The relative entropy values (percentage) were decreased significantly in pilots with TIA as compared with healthy pilots (P＜0.05). Conclusion The dominant frequency uncertainty analysis of alpha band showed clear superiority of computerized evaluation over routine visual assessment for the diagnosis of minor cerebral ischemia. It offers not only a possibility of studying pathophysiological functional parameter, but also the reference for screening procedure in aircrew and astronaut selection.

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Effects of Tea Polyphenols on Cardiac Function and Myocardial Ultrastructure in Rats after Repeated +Gz Stress

Hao ZHAN ; Huajin DONG ; Yimei XIN ; Guixiang TANG

Space Medicine & Medical Engineering.1999;12(2):79-83.

Objective To observe the effects of tea polyphenols (TP) on cardiac function and myocardial ultrastructure in rats after repeated +10 Gz stress. Method Twenty four male Wistar rats were randomly divided into three groups (n=8 each): group A (control), group B (+10 Gz), group C (+Gz with TP). Group B and C were repeatedly exposed to +10 Gz (each for 30 s, onset rate about 0.5 G/s, 3 times/d with +1 Gz 1 min intervals, 3 d/wk, 4 weeks in total), but group A was only submitted to +1 Gz. TP(200 mg.kg-1) was given orally to group C about 1h prior to the +Gz experiment, and distilled water was given to group A and B.Function of isolated rat working hearts and myocardial ultrastructure were observed. Result A significant decrease of left ventricular systolic pressure (LVSP) and injury of myocardial structure in rats were demonstrated after repeated +10 Gz stress. But TP could remarkably elevate the LVSP and improve myocardial ultrastructural injury in +10Gz stressed rats. Conclusion These results indicated that repeated high G exposure may produce cardiac structural and functional injuries in rats which might be partly related to free radical metabolism; and antioxidant TP had significant protective effects on the hearts of +Gz stressed rats.

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Biochemical Changes of Plasma in Paratroops after Parachuting:A Preliminary Investigation

Tangchun WU ; Yili XIONG ; Sheng CHEN ; Shuntang LENG ; Tao HAI ; M.tanguay ROBERT

Space Medicine & Medical Engineering.1999;12(4):235-239.

Objective To study whether physiological and psychological stresses during parachuting jumps may result in biochemical changes of plasma in parachutists. Method Differences in the levels of hormones (cortisol, growth hormone, insulin, pancreatic glucagon, endothelin, angiotonin I and II, aldosterone), activities of enzymes (superoxide dismutase, glutathione peroxidase, glutathione S transferase), levels of the free radical damage indicator malondialdehyde (MDA), tumor necrosis factor alpha (TNF-α), and the main heat stress protein, HSP70,in the plasma and serum were investigated in control (non-parachuting) and parachuting paratroops. Result Significantly higher levels of serum hormones such as growth hormone, insulin, angiotonin I, renin activities, as well as MDA and plasma TNF-α and HSP70 were observed in the parachuting group. Conclusion Whether these changes can potentially serve as useful biomarkers to assess possible abnormal stress in parachutists and to evaluate the health condition and to select parachutists remains to be further studied.

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Hemispheric Asymmetry for Encoding Unrelated Word Pairs? A Functional Near-infrared Spectroscopy Study

Jiongjiong YANG ; Shaoqun ZENG ; Qingming LUO ; Linchu GUAN ; Peizi KUANG ; Hui GONG ; Wemara LICHTY ; Britton CHANCE

Space Medicine & Medical Engineering.2005;18(5):318-323.

Objective To explore the role of the prefrontal cortex in semantic encoding of unrelated word pairs by using functional near-infrared spectroscopy (fNIRS). Method Forty-eight subjects were presented unrelated pairs of Chinese words under both the nonsemantic and semantic encoding conditions. Under the nonsemantic condition, subjects judged whether the two words had similar orthographic structures; under the semantic condition, they generated a sentence involving the presented word pairs. The changes of regional blood volume associated with the cognitive tasks were measured by using fNIRS equipment which was a continuous optical imager. Result The regions that corresponded to the prefrontal regions showed greater activation under semantic than nonsemantic condition in both left and right hemispheres, although the extent of the activation was larger in the left than right prefrontal regions. This result was consistent with other neuroimaging studies on unrelated word pairs processing, but did not conform to the strict interpretations of the hemispheric encoding/retrieval asymmetry model (HERA). Conclusion This study suggests that material specificity is one of the important factors to influence hemispheric asymmetry in memory encoding. When associations between items are required, right prefrontal regions participate in the encoding processing as well. It also indicates that fNIRS imaging is a viable method of investigating higher level cognitive processing such as memory.

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Effects of Tail Suspension on Phosphorylation Status of ERK1/2 in Rat Soleus Muscle

Ming YUAN ; Shizhong JIANG ; Zhili LI ; Desheng WANG

Space Medicine & Medical Engineering.2005;18(5):313-317.

Objective To study the changes of ERK1/2 phosphorylation status induced by unloading of soleus muscle after tail suspension in rats. Method Hindlimb unloading(HU) was produced by tail suspension, which simulated the effect of weightlessness on male Wistar rats. Western blot technique was introduced to detect the total and phospho-ERK1/2 status in isolated soleus muscle of 7 d, 14 d HU and repective control groups. Result Total ERK1/2 in soleus muscle was not affected by 7 d and 14 d HU. The ERK1 phosphorylation status were declined significantly after 7 d and 14 d HU.The ERK2 phosphorylation status were declined significantly after 7 d HU, but not for 14 d HU. Conclusion The unloading of soleus muscle after simulated microgravity can decrease the phosphorylation status of ERK1/2, which may contribute to the atrophy of soleus muscle induced by simulated weightlessness.

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Study of Reentrant Waves in Simulated Myocardial Ischemia

Hong ZHANG ; Zhenxi ZHANG ; Lin YANG ; Yinbin JIN ; Yizhuo HUANG

Space Medicine & Medical Engineering.2005;18(6):399-404.

Objective To study ischemic effects on reentrant activities and cardiac arrhythmias using a computational approach. Method The Noble 98 mathematical model of ventricular cell was used in the study. The operator splitting and adaptive time step methods were utilized to integrate the partial differential equations in cardiac conduction models. The ischemic cells were simulated by decreasing the intracellular ATP concentration, reducing the Na+ conductance, and increasing the extracellular K+ concentration in a two-dimensional tissue. Spiral waves were initiated by the cross field technique. Result The results showed that spiral waves in local severe ischemia displayed three different morphologies,whereas in moderate ischemia only two kinds of wave forms exhibited. When the degree of ischemia reached a critical value, the reentrant wave could break. But for larger areas of ischemia spiral wave formed a typical functional reentry around the obstacle. Conclusion The study demonstrates that size and level of ischemia have effects on VTs and VFs. Large ischemic area is beneficial for maintenance of spiral wave and can provide a high probability in the genesis of VTs. Spiral waves can easily break up and degenerate into VFs under critical area or level of ischemia.

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Automatic Segmentation of Echocardiography Based on a Morphological Reconstruction Algorithm

Xianhua SHEN ; Deyu LI ; Jiangli LIN ; Tianfu WANG ; Xiaohui WEN ; Changqiong ZHENG ; Li RAO ; Hong TANG

Space Medicine & Medical Engineering.2005;18(4):246-250.

Objective To improve the precision of the traditional segmentation of echocardiogram, by suppressing the influence from inherent speckle noises in medical ultrasonic images. Method An automatic segmentation method based on reconstructed morphology was proposed in this paper. First, the opening and closing operations by reconstruction were imposed to the ultrasonic image. Second, the top-hat operation was used to extract the bright and/or dark features and to find out the boundaries corresponding to these features, whereby implemented the automatic segmentation. Result The segmented echocardiogram had less artificial boundaries resulted from speckle noise, and could accurately be extracted the artery and ventricle. Conclusion The presented method can detect both dark and bright objects accurately, and the boundary has a fine continuity. In addition, the algorithm is also applicable to the extraction of sole bright/dark features, accordingly to reduce the complexity and time needed and to improve the accuracy.

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A Non-rigid Medical Image Registration Algorithm Based on Modally Controlled Free Form Deformation

Yongming ZHAO ; Su ZHANG ; Zhao ZHANG ; Yazhu CHEN

Space Medicine & Medical Engineering.2005;18(4):240-245.

Objective To register pre-operative MRI/CT images with intra-operative ultrasound images based on vessels visible in both of the modalities. Method A non-rigid registration method of multimodal medical images based on Free Form Deformation(FFD) was proposed. When the images were aligned, the centerline points of the vessels in one image aligned with the intensity ridge points in the other image. Rigid transformation was adopted in global registration while local deformation was described by a Free Form Deformation based on a modally controlled B-spline. The method applied an optimization strategy combining the genetic algorithm with the conjugated gradients algorithm to minimize the objective function. Result Two experiments were designed on phantom and clinical data to evaluate the method. The results demonstrated that the registration method was consistent accurate. The average standard deviation of the final transformation parameters was sub-voxel, sub-millimeter, and within 0.010 radians. Conclusion The results show that the method has good registration accuracy and convergence rate. It can be applied efficiently in the ultrasound-image-guided surgery system.

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Measurement and Evaluation of Environmental Factors in Underground Construction Site

Rong YANG ; Jianhua LIU ; Songmei LI ; Xuanjun WANG

Space Medicine & Medical Engineering.2005;18(4):235-239.

Objective To Evaluate the environment quality in underground construction site based on the measurement of atmosphere composition and microclimate. Method Concentrations and composition of gases were analyzed by combined detection with mass spectrometer and gas chromatograph. Microbial content was detected by striking method. A microclimate model was built based on the measurements of temperature, humidity and wind speed in two years. Result Concentrations of inorganic gas was higher than national standard. Total volatile organic compounds were in the range of 4～6 mg/m3, which highly exceeded the national standard. Concentration of O2 descended obviously at the time when personnel went into the construction site, and was lower than the national standard of 299 mg/m3 after continuous working for 3 h. When an aerator was started, the average noise level was in the range of 70～93 dB, which was higher than the national standard(55～70 dB). In the course of working, the average microbial content reached 4 000 cfu/m3 which was 3 times as high as the background level. The microclimate characteristic with high humidity, low temperature and inadequate sunshine was unsuitable for dwelling. Conclusion Environment in the underground construction site is unfavorable as compared with that on the ground. The physiological function of working staff may be influenced obviously due to cumulative effect of the above mentioned factors, and may lead to aprosexia, hypomnesis, fatigue, etc. Six kinds of protection means are suggested in the paper.

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Changes of Hippocampus Somatostatin and Learning Ability in Rats after+Gz Exposure

Xinsheng CAO ; Xiqing SUN ; Yanhong WU ; Xingyu WU ; Tingsong LIU ; Shu ZHANG

Space Medicine & Medical Engineering.2005;18(2):79-83.

Objective To investigate changes of learning ability and somatostatin (SS) changes after positive acceleration (+Gz) exposures. Mehtod Eighty male SD rats were randomly divided into 3groups: control group(Con), +6 Gz/3 min group ( +6 Gz), and +10 Gz/3 min group ( +10 Gz),8 rats in each group. Changes of learning ability in rats were observed at 0 d, 2 d, 4 d and 6 d after + Gz exposure. SS in hippocampus was measured by RIA at 0 d, 2 d and 4 d after + Gz exposures ( there were 8 rats every time, in each group). Result In Y-maze test,number of correct response decreased significantly (P ＜0.01 ), and total reaction time increased significantly(P ＜0.01 ) in +6Gz and +10 Gz groups as compared with control group; number of correct response and total reaction time in +10 Gz group changed significantly at 0 d(P ＜0.01 or P ＜0.05) as compared with +6Gz group. RIA showed that, content of SS in hippocampus declined at 0 d and 2 d(P ＜0.05 or P ＜0.01) in +6 Gz and + 10 Gz groups as compared with control group. Conclusion + Gz exposure could impair learning ability of rats, and inhibit expression of SS in hippocampus.

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