Biomedical subjects

Yong-jie Yao

Publications and source records attributed to Yong-jie Yao.

11 recordsLinked to original sources

PubMed2004

[Effects of repeated lower g exposures on high-G induced memory and balance changes in rats].

OBJECTIVE: To study the protective effects of repeated +4 Gz/3 min exposures on memory and balance changes induced by +10 Gz/5 min exposure in rats. METHOD: 32 male SD rats were randomly divided into 4 groups: control group (C) ; +10 Gz/5 min group (10 Gz); 3 d training group (3 d) ; 5 d training (5 d) group (exposed to +4 Gz/3 min per day for 3 or 5 days before +10 Gz/5 min exposure). Changes of memory and balance in rats of all the 4 groups were observed after +10 Gz/5 min exposure. RESULT: In +10 Gz group, the percentage of correct reaction (CR) decreased significantly at all times after +10 Gz exposure (P<0.01), and the reaction time (RT) lengthened significantly at all times after +10 Gz exposure (P<0.01); as compared with control group. In 3 d training group, CR decreased significantly at 1 d, 2 d and 6 d after +10 Gz exposure (P<0.05), RT lengthened significantly at all times after +10 Gz exposure (P<0.05); as compared with control group. CR increased significantly at 2 d, 4 d and 6 d after +10 Gz exposure (P<0.01), RT shortened significantly at 1 d, 2 d, 4 d and 6 d after +10 Gz exposure (P<0.01) as compared with +10 Gz group. In 5 d training group, there were no apparent changes compared to control group; but CR increased significantly and RT shortened significantly at the time of 1 d, 2 d, 4 d and 6 d after +10 Gz exposure (P<0.01) as compared with +10 Gz group. Balancing function (BF) of +10 Gz group decreased significantly immediately and 2 d after +10 Gz exposure (P<0.01) as compared with control group. BF in 3 d and 5 d training group improved significantly immediately and 2 d after +10 Gz exposure as compared with +10 Gz group (P<0.01). CONCLUSION: It is suggested that repeated low +Gz exposures could provide protective effect on memory and balance changes induced by high +Gz exposure in rats.

Acceleration↗

PubMed2004

[Effects of self-generated LBNP training on cardiovascular function and lower body negative pressure (LBNP) tolerance].

OBJECTIVE: To explore the changes of cardiac function and lower body negative pressure tolerance after self-generated Lower Body Negative Pressure device training and provide experimental evidences for its appliance. METHOD: Twelve healthy male subjects were randomly divided into two groups, and received training on two conditions for entirely closing the valve or opening to -30 mmHg of peak LBNP separately. The group A was trained for five days and three minutes per day. Heartfunction, HUT and tolerance of LBNP were measured in pre-training, 3 d and post-training. The group B was trained for ten days and five minutes each day. All the measurements that was the same as in group A were made. RESULT: Heart function of group A decreased and tolerance of LBNP increased significantly (P<0.05). In group B, heart function increased significantly after 8 days training, so did tolerance of LBNP. CONCLUSION: It suggested that lower body negative pressure tolerance could be improved by self-generated Lower Body Negative Pressure device training. The changes of cardiac function, however, were based on the project of training.

Adaptation, Physiological↗

PubMed2003

[Development and application of self-powered short arm human centrifuge].

OBJECTIVE: To present the development and application of a self-powered short arm human centrifuge. METHOD: Self-powered short arm human centrifuge consisted of human power, adjustable resistance trig, short arm and supporting construction parts. It was driven by human power. The short arm turned around the supporting part so artificial gravity is produced. The physical load can be adjusted by the adjustable resistance part. G-level depends on the rotative velocity of the central shaft. Nine healthy male volunteers received self-powered short arm human centrifuge training for 5 min per day with rotative velocity of 30-34 r min-1 for 7 d. Cardiac pumping function was measured before and after training. RESULT: Heart rate (HR) decreased significantly while left ventricular ejection time (LVET) increased significantly after 3 d training, and HR and LVET changed further after 7 d training. Stroke volume increased significantly only after 7 d training. CONCLUSION: Self-powered short arm human centrifuge combines artificial gravity and exercise and included other advantages of safety and economy of construction. Cardiac pumping function could be improved by 7 d training. It may be used for anti-G physiological training or as a countermeasure to counteract the effect of microgravity.

Adaptation, Physiological↗

PubMed2003

[Effects of +Gz exposure time on memory and behavior in rats].

OBJECTIVE: To explore the effect of +Gz exposure time on memory and behavior in rats. METHOD: Twenty-four male SD rats were randomly divided into control group (A), +10 Gz/3 min group (B) and +10 Gz/5 min group (C). Rats in group A and B were exposed to +10 Gz for 3 min or 5 min respectively. Changes of memory and behavior in rats were observed after +Gz exposure. RESULT: As compared with control, percentage of right reflex decreased significantly and reaction time lengthened significantly immediately, 1 d, 2 d, 4 d and 6 d after +10 Gz/5 min exposure (P<0.01); reaction time lengthened significantly immediately and 2 d after +10 Gz/3 min exposure (P< 0.01). As compared with +10 Gz/3 min, percentage of right reflex decreased significantly and reaction time lengthened significantly at 1 d, 2 d, 4 d and 6 d after +10 Gz/5 min exposure (P<0.01). As compared with control and +10 Gz/3 min, time stayed in center grille lengthened significantly immediately after +10 Gz/5 min exposure (P<0.01); balancing function decreased significantly immediately and 2 d after +10 Gz/5 min exposure (P< 0.01). CONCLUSION: It is suggested that +10 Gz/ 3 min exposure may induce a provisional disturbance in memory function and a change in behavior in rats, and +10 Gz/5 min exposure may induce a sustained disturbance in memory function and an obvious change in behavior in rats.

Acceleration↗

PubMed2003

[Weightlessness or weightlessness simulation and vascular remodeling].

Weightlessness is inavoidable during spaceflight. It brings profound physiological effects on human body. Vascular remodeling is one of the important changes of cardiovascular system caused by weightlessness or simulated weightlessness. The paper summarized the studies on the effects of weightlessness or weightlessness simulation on vascular remodeling in recent years. The emergence and development of the concept of vascular remodeling were briefly reviewed. The advances of study on vascular remodeling in recent years was briefly discussed with the points focused on the effects of weightlessness or weightlessness simulation on cardiovascular remodeling and its mechanism. It is proposed that cardiovascular remodeling might be important in studying the causes of orthostatic intolerance after spaceflight.

Adaptation, Physiological↗

PubMed2003

[Development of self-generating lower body negative pressure device].

OBJECTIVE: To develop a kind of self-generating lower body negative pressure device. METHOD: The device consists of a flexible bellows, reinforced by several steel rings and sealed by gasproof adhesive plaster. An adjustable valve, a one-way flap valve, shoulder straps and handles are incorporated on the top of the bellows. The user's lower body was contained in the bellows. As the user's legs were extended, the bellows was elongated and the air pressure in it decreased. RESULT: Negative pressures of -58, -46, -38 and -26 mm-Hg respectively was created with the adjustable inlet valve completely closed, one-quarter open, half open, or fully open. CONCLUSION: This self-generating lower body negative pressure device combines exercise and LBNP into one thing and is safe and easy to use. It might be used in preventing cardiovascular deconditioning during spaceflight or for anti-G training of pilots.

Aerospace Medicine↗

PubMed2002

[Effects of lower body negative pressure in the first and last week during 21 d head-down bed rest on orthostatic tolerance and cardiac function].

OBJECTIVE: To investigate the changes of orthostatic tolerance and cardiac function during 21 d head-down tilt (HDT) bed rest and effect of lower body negative pressure (LBNP) in the first and the last weeks in humans. METHOD: Twelve healthy male volunteers were exposed to -6 degrees HDT bed rest for 21 d. Six subjects received -30 mmHg LBNP sessions for 1 h/d from the 1st to the 7th day and from the 15th to the 21st day of the HDT, and the other six who did not receive LBNP served as control. Orthostatic tolerance was assessed by means of standard tilt test. The cardiac pumping function and cardiac systolic function were measured before and during HDT. RESULT: Before HDT, all the subjects in the two groups completed the tilt tests. After 10 d and 21 d of HDT, all the subjects of the control group and one subject of the LBNP group could not complete the tilt test due to presyncopal or syncopal symptoms. The mean time of upright standing in the control group (15.0 +/- 3.2 min) was significantly shorter than those in the LBNP group (19.7 +/- 0.9 min). The stroke volume and cardiac output decreased significantly in the control group on days 3 and 10 of HDT, but remained unchanged throughout HDT in the LBNP group. A significant increase in preejection period (PEP)/left ventricular ejection time (LVET) was observed on days 3 and 14 of HDT in both groups. The PEP/LVET in the LBNP group was significantly lower than those in the control group on days 3 of HDT, while LVET in LBNP group was significantly higher than those in the control group on days 3, 7 and 14 of HDT. CONCLUSION: It is suggested that the brief daily LBNP sessions in the first and the last weeks were effective in preventing orthostatic intolerance and the reduction of cardiac pumping function and cardiac systole function induced by 21 d HDT bed rest.

Adult↗

PubMed2002

[Upright tilt table testing and syncope evaluation].

Syncope is a state of unconsciousness, the process of syncope is sudden and transient. Transient and widespread cerebral ischemia/hypoxia are the reasons of syncope. Sixty percent to seventy percent of the patients suffering from syncope have no categorical reasoning, although lots of assisted examinations had been carried out. Those syncope are called unexplained syncope or unknown origin syncope. Basic upright tilt table test, as well as isoproterenol tilt table test, is a quite effective diagnostic technique for unexplained syncope. This paper reviewed the value of upright tilt [correction of tile] table test in diagnosing unexplained syncope. The method of experiment, information of it's clinical application and points for attention with test were also introduced.

Brain Ischemia↗

PubMed2002

[Changes of serum alkaline phosphatase and electrolytes during 21 d head down bed-rest].

Objective. To investigate the effect of simulated weightlessness on serum alkaline phosphatase (ALP), calcium, magnesium, chlorine and phosphorus. Method. 6 healthy males, aged 24.8 +/- 6.1, were exposed to -6 degrees HDT bed rest for 21 d. Activity of serum alkaline phosphatase, serum contents of calcium (Ca), magnesium (Mg), chlorine (Cl) and phosphorus (P) ions were assayed before HDT (d-3), on the 3rd, 10th and 21st day during HDT and after HDT (d+2). Ca was measured by methyl thymol blue method, P was determined with ultraviolet spectrophotography, determination of Mg and Cl were made with enzyme method, ALP was examined with 4-nitrobenzene phosphate method. Result. Serum Ca2+ levels were significantly higher at d10, d2l and d+2 than the value of d-3 (P<0.01). P3+ levels declined significantly on d2l as compared with d-3 (P<0.01). During the HDT and after HDT, Mg2+ declined to a level below that before HDT (P<0.05 or P<0.01). Cl- were significantly higher at d2l and d+2 than the value of d-3 (P<0.01). ALP level was higher on d2l than on d-3 (P<0.01). Conclusion. 21 d HDT induced increase of Ca, Cl, ALP, and decline of Mg and P. The changes may reflect the imbalance of metabolism.

Adult↗

PubMed2002

[Effects of simulated microgravity on cardiovascular function and counter effect of lower body negative pressure].

Studies on effect of simulated microgravity on cardiovascular function and counter effect of lower body negative pressure (LBNP) in recent years were summarized. The mechanism of simulated microgravity induced orthostatic intolerance may involve the reduction of cardiovascular function and cerebral blood flow, and endocrine changes. The significance of mathematical model in the study of mechanism of microgravity induced orthostatic intolerance was also discussed. The counter effect of LBNP was emphasized.

Bed Rest↗

PubMed2002

[Effects of simulated weightlessness on pressure-volume relationships of femoral vein of New Zealand Rabbits].

Objective. To observe the changes of pressure-volume relationships of rabbit femoral veins and their structural changes caused by simulated weightlessness. Method. Head-Down Tilt (HDT) -20 degrees rabbit model was used to simulate weightlessness. Twenty four healthy male New Zealand Rabbits were randomly divided into 21 d HDT group,10 d HDT group and control group, (8 in each group). Pressure-volume (P-V) relationship of rabbits femoral veins was measured and the microstructure of the veins was observed. Result. The femoral vein P-V relationship curves of HDT groups showed a larger volume change ratio than that of control group. This change was that 21 d HDT group was even more obvious than that of HDT-10 d group. B1 and B2 in quadratic equations of 21 d HDT group were significantly higher than the values of both 10 d HDT group and control group during expansion (inflow) and collapse (outflow) (P<0.01). The result of histological examination showed that the contents and structure of femoral vein wall of HDT-rabbits changed significantly. Endothelial cells of femoral vein became short and columnar or cubic, some of which fell off. Smooth muscle layer became thinner. Conclusion. Femoral venous compliance increased after weightlessness-simulation and the femoral venous compliance in 21 d-HDT rabbits increased more obviously than that in 10 d-HDT rabbits. The structure of femoral vein wall had changed obviously.

Adaptation, Physiological↗