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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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Autonomic Nervous Response to Cold Provocation in Vibration-Induced White Finger(VWF) Patients with HRV Analysis

Jin LUO ; Hisataka SAKAKIBARA ; Shankuan ZHU

Space Medicine & Medical Engineering.1999;12(1):6-9.

Objective To evaluate the autonomic nervous response of Vibration-induced white finger(VWF) patients to cold provocation test by power spectral analysis of heart rate variability(HRV).Methods The cold provocation test was conducted in 22 VWF patients and 19 healthy volunteers.ECG was recorded during the experiment,and converted to R-R interval signals after the experiment.The normalized LF[(0.02～0.15) Hz]component power,normalized HF[(0.15～0.40) Hz] component power and the ratio of LF to HF power(LF/HF ratio) were calculated.Results At the beginning of cold exposure,there were a significant decrease of HF% in both groups,and a significant increase of LF/HF ratio in VWF group as compared with pre-exposure value.The LF/HF ratio in VWF group during cold exposure was significantly higher than that in the control group.Conclusion Cold stimuli induced depression of parasympathetic nervous system in both groups,and the sympatho-vagal balance was maintained in the control group,but in VWF group it became sympathetic dominance during cold exposure.The sympathetic nervous system of VWF patients may be hyperreactive to cold stimuli.

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Effects of Tea Polyphenols on Cerebral Lipid Peroxidation,Liver and Renal Functions in Rats after Repeated +Gz Stress

Hao ZHAN ; Yimei XIN ; Guixiang TANG ; Liming CHEN ; Jing WEN

Space Medicine & Medical Engineering.1999;12(1):1-5.

Objective To observe the effects of repeated +10 Gz stress on cerebral lipid peroxidation,liver and renal function in rats and the prophylactic effects of antioxidant tea polyphenols(TP).Method Twenty-four male Wistar rats were randomly divided into three groups(n=8 each):group A(control),group B(+10 Gz),and group C(TP).Group B and C were exposed to repeated +10 Gz stress(each for 30s,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) was given orally in group C about 1 h prior to the +Gz experiment,while distilled water was given in group A and B.Lipid peroxidation in the brain,liver and renal functions and serum lipids were determined.Results As compared with the control,lipid peroxidation in rat cerebral homogenate,mitochondria and cytoplasm was significantly increased( P<0.05),and serum creatinine concentration was markedly elevated after repeated +10 Gz stress(P<0.01).But,TP had significant inhibitory effect on +10 Gz stress induced peroxidative injury in rat brain and reduced the serum creatinine level.There were no differences of serum triglyceride and total cholesterol concentrations and glutamic-pyruvic transaminase activity among the three groups.Conclusion These results indicated that repeated high +Gz stress could bring about peroxidative injury in brain and harmful effect on renal function,and natural antioxidant TP had signficant protective effects.

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Expression of HSP70 Gene in Rat Brain after Exposures to Repeated +Gz

Qing CAI ; Hongjin LIU ; Youchun CHEN ; Guiying JI ; Tongxin CHEN

Space Medicine & Medical Engineering.1999;12(5):313-317.

Objective To study the changes of mRNA expression of heat shock protein 70 (HSP70) in the rat brain exposed to repeated +Gz. Method The mRNA expression levels of HSP70 in rat brain were measured by semi-quantitative reverse transcription polymerase chain reaction (RT-PCR). Result The HSP70 mRNA expression levels in rat brains taken 30 min and 6 h after repeated +Gz exposures were significantly higher than those in control group, while the difference between the levels of control group and those of experimental rat brains taken 24 h after +Gz exposure was not significant. Conclusion It is suggested that HSP70 mRNA expression in rat brain can be induced by repeated +Gz exposures and the increased HSP70 mRNA expression may play an important role in self-protection against brain damage induced by+Gz exposures.

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Changes in Vasoreactivity of Rat Pulmonary Artery after 7 d Tail-suspension

Lei SUN ; Desheng WANG ; Wei REN ; Qiulu XIANG

Space Medicine & Medical Engineering.2001;14(1):-5.

Objective To clarify the effects of simulated microgravity on the local regulating function of the pulmonary circulation. Method Rat tail-suspension(TS) was used as the animal model to simulate the effects of microgravity.The changes in responses of pulmonary artery to several vasoactive agents were determined by using in vitro vessel rings perfusion technique. Result As for the endothelium-intact vessel rings from TS group compared with those from the control(C) group,the contractile responses of pulmonary artery to potassium chloride (KCl,10～70 mmol/L) did not change obviously after 7 d tail-suspension,which were markedly diminished as to phenylephrine (PE,10-9～10-5mol/L).The vasodilatory responses to acetylcholine (ACh,10-9～10-5mol/L) were markedly enhanced,which did not change obviously as to captopril (Cap,10-5～3×10-3 mol/L).The vasoreactivity of endothelium-removed pulmonary artery rings to all vasoactive agents did not change after 7 d tail-suspension as compared with those from control rats. Conclusion The release of nitric oxide (NO) by rat pulmonary arterial endothelium was enhanced after 7 d tail-suspension.The vasodilatory function of pulmonary artery was enhanced.

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Genetic Construction and Characterization of Murine Interleukin-18 Immunotoxin with a Truncated Pseudomonas Exotoxin

Hong LI ; Mingyuan LI ; Meili LV ; Zhonghua JIANG ; Lin ZHANG

Space Medicine & Medical Engineering.2005;18(6):395-398.

Objective To construct a new recombinant immunotoxin expression vector fused with a murine interleukin18(IL18) gene and a truncated pseudomonas exotoxin (PE38) gene, and examine the expression of IL-18-PE38 fusion protein in Escherichia coli (E. coli). Method Murine IL-18 (mIL-18) cDNA was cloned from murine liver tissue through reverse transcription-polymerase chain reaction (RT-PCR). The mIL-18 cDNA was ligased with a PE38 gene carried by PRKL expression vector through T4 DNA ligase and constructed into fusion protein expression plasmid PRKL-IL18-PE38. The recombinant vector was identified by restriction endonucleases digestion, PCR and DNA sequencing. After transformed into E.coli BL21 and induced by IPTG, the expressed product was obtained and the molecular weight and specificity were determined by SDS-PAGE and Western-blotting. Result The new recombinant immunotoxin expression vector was constructed successfully. DNA sequencing revealed that the mIL-18 and PE38 gene were consistent with NCBI Gene Bank. The IL-18-PE38 fusion protein was expressed in E.coli BL21, and Western-blotting analysis indicated that the molecular weight of the expression product is about 56 kDa, and could react with the specific antibody against mIL-18. Conclusion IL-18-PE38 recombinant immunotoxin expression vector will provide the basis for study on the targeted cytotoxic activity to Th1 cells and may have some potential value in the treatment of Th1 cell-mediated autoimmune diseases.

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A Preliminary Study on Non-invasive Measurement of Intra-abdominal Pressure

Xia LI ; Jing BAI ; Jian SUN ; Kui YING ; Canxing XU ; Yu MAO ; Tong LI

Space Medicine & Medical Engineering.2005;18(6):391-394.

Objective To present a new method and design of an instrument for measuring intra-abdominal pressure (IAP) non-invasively. Method A pressure sensor (YH-4) and a displacement sensor (sliding rheostat) were assembled into a probe so that they work in a linear mode. When this assembled instrument probe acts on the abdominal wall of a subject, a pressure as called the external abdominal pressure (EAP), and a corresponding displacement were detected. A relationship was established mathematically between the IAP measured by non-invasive and invasive method, and IAP was calculated by EAP measurement indirectly non-invasively. Result The method was testified by animal experiment in rabbits. And the preliminary results indicated that linear relation between EAP and IAP was obtained. Conclusion Feasibility of the new method is validated by animal experiment. It provides scientific evidence for further clinical experiment.

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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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