Obiective To set up a method of scaffold evaluation using human cell line as seed cells and screen appropriate scaffold for live tissue engineering, Methods HepG2 cells were plated onto biodegradable polymer scaffolds: PLGA, 3% chitosan (3%CS) and 2% silk fibroin (2%SF), and cultured in vitro. The growth, distribution and function of HepG2 cells in the scaffolds were evaluated using MTT assay, H.E. staining, and urea assay kit. Results HepG2 cells plated on the three scaffolds maintained a proliferative state. In contrast, the cells on the 2%SF proliferated strongly, while the cells on the PLGA and chitin proliferated poorly. Histological examination showed that HepG2 cells distributed evenly on the 2%SF scaffold with a high amount, while few cells could be found on the PLGA and ehitin at day 7. Cell function assay showed that HepG2 cells on the 2%SF and PLGA exhibited slower decrease of urea synthesis compared to HepG2 cells on the chitosan. Conclusion The three scaffolds have good biocompatibility. In contrast, 2%SF scaffold is more appropriate for liver tissue engineering. This method may be used for scale screening of scaffolds for liver tissue engineering.

BACKGROUND: Neonatal rat liver cells are moderately differentiated cells with the characterization and function of both liver progenitors and hepatocytes, thus, it is an ideal cell source for the study of the hepatocyte characterization. OBJECTIVE: To explore the isolation and in vitro culture of neonatal rat liver cells.DESIGN, TIME AND SETTING: An in vitro cytology trial was carried out at the Institute of General Surgery, General Hospital of Chinese PLA from March to August 2008.MATERIALS: Neonatal SD rats with 3 months old were used, irrespective of genders.METHODS: Liver cells from neonatal rat were isolated by tissue piece-cold trypsin digestion combining with multi-step low centrifuge, and cultured onto the plate in HepatoZYME-SFM supplemented with 10% fetal serum. The growth and function of the cultured liver cells was evaluated by contrast microscopy, MTT assay, PAS staining and urine enzyme test. MAIN OUTCOME MEASURES: Cell morphology and viability, content of glycogen, as well as urea level in the supernatant.RESULTS: Totally 1.0×10~6-2×10~6 cells per whole liver could be obtained with viability above 90%. The cells displayed round or orbicular-ovate shapes with big nuclei, and cell body was smaller than mature cells. More than 95% purity achieved after removal erythrocyte, nonparenchymal cells and dead cells with multi-step low-speed centrifugalization. The viability of cells were gradually increased at the beginning of culture, noticeably alleviated at the 3 days, and reached a peak at the 11 days, and then gradually decreased. The difference between day 1 and days 11, as well as days 15 and days 11 had significance (P=0). Liver cells cultured in HepatoZYME-SFM attached and kept hepatocyte-specific morphology. PAS staining showed the cultured liver cells at day 7 were strongly positive and then the positive cells decreased gradually, until 15 days, only few positive cells could be seen. Urea level in the supernatant remained stable at the initial time and dramatically decreased after 7-day culture. CONCLUSION: The tissue piece-cold trypsin digestion and HepatoZYME-SFM is a simple and efficient isolation and culture system for neonatal rat liver cells.

BACKGROUND:N-methyl-D-aspartate receptor is an ionic glutamate receptor which is closely related with the neural synaptic plasticity, and also can regulate neural synaptic plasticity. OBJECTIVE:To explore the mechanism by which N-methyl-D-aspartate receptor subunits NR2A and NR2B regulate neural synaptic plasticity after cerebral ischemia. METHODS: 60 Wister rats were randomly and evenly divided into a sham-operated group and a cerebral ischemia group. Rat models of chronic cerebral ischemia were established using the modified bilateral common carotid artery occlusion method in the cerebral ischemia group, while rats in the sham-operated group did not undergo occlusion of the common carotid artery and vagus nerve. RESULTS AND CONCLUSION:At 0-12 hours after chronic cerebral ischemia, NR2A expression in the rat hippocampus was gradualy decreased, while the expression of NR2B reached its peak level at 4 hours after cerebral ischemia. Under the circumstance of cerebral ischemia, neither low frequency nor high frequency induced long-term potentiation. These findings suggest that NR2B exhibit inhibitory effect, while NR2A exhibit promoting effect on long-term potentiation induced by stimulation.

Objective To explore the teaching effects of Lecture Based Learning (LBL) incorporated with Case Based Learning (CBL) and Problem Based Learning (PBL) methods in the teach-ing of anatomy.Methods 740 students of Grades 2012 and 2013 from clinical medical major were chosen as the subjects,randomly divided into experimental and control groups.LBL was conducted in the control group of 644 students,while LBL+PBL+CBL method was applied in the experimental group of 96 students.After completion of the course,all students were surveyed with the questionnaire and tested with specimen and theoretical examinations.The data was collected and analyzed with SPSS 17.0 and two sample U tests.Results The students' time of learning anatomy in the control group outside classroom teaching was (105 ± 25) minutes per week,while the students' time of learning anatomy in the experimental group was (190 ± 25) minutes per week.The difference was statistically significant (t=31.08,P=0.000).The difference of after-class total learn-ing time was also statistically significant between two groups(t=27.42,P=0.000).Percentages of satisfaction with teaching methods for control group were 87.5％ and 87％,while for the experimental group 98％ and 100％.Kruskal-Wallis test showed there were significant differences in experimental groups of grades 2012(x2=31.19,P=0.000) and 2013 (x2=40.35,P=0.000) compared with control group.Comparison of both groups' results of the examinations was statistically significant concerning multiple choices,essays and case analysis questions (P＜0.05).Conclusion Teaching method of LBL incorporated with PBL and CBL was significantly effective than that of the sole traditional LBL method,which indicated its practice value.

Objective To study genetic polymorphism of 6 Y chromosomal STR in Hui ethnic group living in Ningxia Hui ethnic autonomous region, in order to evaluate their usefulness in forensic science and enrich the Chinese genetic information resources. Methods We investigated 101 unrelated, healthy, male individuals of Hui ethnic group and studied their allelic frequency distribution and haplotype diversity of 6 Y chromosomal STR. Primer for each loci was labeled with the fluorescent by FAM (blue) or TAMRA(yellow). The data of Hui ethnic group were generated co-amplification, GeneScan, genotype, and genetic distribution analysis. Results 31 alleles and 43 phenotype(DYS385) were detected, with the frequencies ranging from 0.0099-0.7129. Out of a total of 101 individuals, 96 showed different haplotypes; 91 were unique; 5 were found 2 times. The haplotype diversity for 6 Y-STR loci was 0.9990. Conclusion The date obtained can be valuable for individual identification, paternity testing in forensic fields and for population genetics because of 6 Y-STR loci high polymorphism.

Objective To evaluate the noise hazard level of a coal mining enterprise, and identify high-risk operation types and people, and to provide a basis for preventing and controlling the health damage caused by noise. Methods A large coal mining enterprise in Shaanxi Province was selected as the research object. The noise monitoring data of the coal mine over the years was used to calculate the noise exposure matrix of each post in the enterprise, and the classification of occupational hazards at workplaces (GBZ/T 229.4-2012) was used to assess the occupational health risk levels. Results Among the 22 noise-exposed positions in the enterprise, the 8-hour working day equivalent sound level in positions of shearer driver, horseshoe driver, crusher driver, shuttle driver, relaxation screen driver, and grading screen driver were all higher than the occupational exposure limit of noise. In 2021, the noise exposure levels of shearer drivers, crusher drivers, and coal-selecting workers were all higher than 90 dB (A), and the occupational hazard level was moderate hazard level. In addition, the noise exposure levels of most other jobs also exceeded the occupational exposure limit. Conclusion The noise hazards in the coal mine industry are mainly concentrated in the posts of the coal mining system, tunneling system, and screening workshop. Among them, the shearer driver, the crusher driver, and the coal preparation workers have higher noise exposure levels. It is recommended to take corresponding noise reduction measures and strengthen the protection level to reduce the noise exposure risk of workers.