[The Antileukemia Activity of ZSTK474 on U937 Cells].

OBJECTIVE: To investigate the antileukemia activity of phosphatidylinositol-3 kinase (PI3K) inhibitor ZSTK474 on human leukemia cell line U937. METHODS: MTT, soft agar assay, flow cytometric analysis and western blot were used to detect the effect of ZSTK474 on U937 cell proliferation, tumorigenicity, cell cycle, cell apoptosis and phosphorylation levels of the key factor of PI3K/AKT pathway. Chou-Talalay method was used to evaluate the combination of ZSTK474 with Cytarabine or Homoharringtonine. RESULTS: PI3K inhibitor ZSTK474 could inhibit the proliferation and tumorigenicity of U937 cell, induce G1 cell cycle arrest and promote cell apoptosis, and enhance intracellular ROS production and decrease MMP, downregulate Cyclin D1, p-Rb, BCL-2 and upregulate p27, caspase-9, caspase-3, PARP and BAX. Furthermore, the phosphorylation of PDK1, GSK-3ß, AKT and mTOR could be downregulated by ZSTK474. The combination of ZSTK474 with Homoharringtonine was synergistic. CONCLUSION: ZSTK474 can inhibit the pathway of PI3K/AKT, ZSTK474 alone or in combination with Homoharringtonine shows potential antileukemia activity on U937 cells.

[Effects of digital information display time on human and machines monitoring performance].

OBJECTIVE: To provide an index for function allocation of information monitoring between human and machine by studying the effect of digital information display time on human or machine monitoring performance. METHOD: Two computers were used. One computer, ten numbers with two decided digits were displayed randomly for three times. The display time varied from 200 ms to 5000 ms with different intervals. The other's monitor was simulated by a camera recorder and image identifying arithmetics was designed. Subjects watched the CRT and press the computer keys related with the figure on the CRT. In every experiment, the correct rate of human press or machine identification was recorded. RESULT: The subjects' correct rate varied sharply when display time was 1500 ms. When display time was shorter then 1500 ms, subjects' correct rate decreased accordingly and may approach 0. From 1500 ms to 4500 ms, the subjects' correct rate was close to 100.0%. But when the display time was 5000 ms, the subjects' correct rate decreased slightly to 97.67%. From 50 ms to 5000 ms, the machine's correct rate varied little at different display times. CONCLUSION: The digital display time has very great effect on human monitoring performance. But it has little effect on machine performance.

[Experimental study on human reaction of determination and performance in virtual environment].

OBJECTIVE: To study factuality of ergonomic experimental data from subjects performing virtual environment wearing head mounted display (HMD) and data gloves, so as to improve the reliability of the application of virtual reality in manned spaceflight (e.g. human-machine interface design scheme ergonomic evaluation, and virtual training). METHOD: Experiment in a virtual module is designed and implemented on the virtual reality ergonomic experimental system. First, pre-experiments are done to determine the different levels of objects to be operated and the height of a virtual table which is in the virtual module. On the basis of the pre-experiments, the formal experiments are completed. In addition, a virtual reality questionnaire (VRQ) is developed and employed in order to assess subjective impressions of the virtual environment. RESULT: Normal distribution of performing time is shown when a virtual sphere is put into a drawer of standard cabinet of virtual module on a front table by subjects wearing HMD, its mean value being 36.72 s and variance being 13.798 s. By VRQ analysis, about 70.2% of the subjects thought that HMD has a good stereo quality, they can be immersed in the virtual module. CONCLUSION: When virtual reality is applied in ergonomic evaluation or virtual training, the HMD and data glove of the system would satisfy the requirements of human-computer interaction, so that human performance can be analogized and corresponding truth of experimental result can be achieved.

[Effects of field viewing angles on object judgement [correction of jubgerent] in virtual environment].

OBJECT: To investigate the effect of viewing angle on human judgement reliability for objects in virtual environment. METHOD: Firstly, pre-tests were done with the PC virtual reality ergonomic system to determine difference among observed object and values of viewing angle. Then, one factor, 4-levels full random experiments were done with 45 health human subjects (male and female nearly 1:1). RESULT: It was shown that the reliability of human judgement was significantly influenced by the setting of the viewing angle of virtual environment, and the object judgement including size and angle judgement was the best when the viewing angle of virtual environment was 60 degrees. CONCLUSION: When virtual reality was used in ergonomic design, operation training and other related research, the effect of field viewing angle should be taken into consideration, and 60 degrees is recommended to be optimal for human judgment task.

[Human-centered ergonomical study and applications in manned spacecraft project of China].

High G and weightlessness are two important environment factors that are unavoidable during spaceflight. They will bring key effects on astronauts' posture and working efficiency. In this paper, on the basis of experience of China first manned spacecraft project in the past 10 years, the concept of space ergonomics and its role in the project were reviewed. Ergonomic research items and corresponding methods were systematically analyzed with astronauts' working state, and ergonomic evaluation types and approaches were discussed with some given cases being used in the project. Finally, some suggestions were proposed on space man-machine system development according to recent ergonomic trend in space ergonomics and the basis of experience of first manned spacecraft project.