AIM:To study the effects of Se-methylselenocysteine(MSC) on the growth and apoptosis of human liver carcinoma cell line,HepG_2 cells and the molecular mechanism of effects.METHODS: After HepG_2 cells treated with various concentrations of MSC,survival and apoptosis were determined by MTT assay and light microscope,apoptosis and cell cycle were determined by flow cytometry.Malignant phenotype was determined by soft agarose growth assay.Cyclin D1 mRNA expression was determined by RT-PCR and Caspase-3 activity was measured by Caspase-3 activity assay kit.RESULTS: After being treated with 25(?mol?L~(-1)) MSC for 24 h,the survival of HepG_2 cells was decreased,a marked apoptosis and S phase arrest characteristic was observed in time-and dose-dependent manner.Soft agatose growth assay showed MSC inhibited HepG_2 cells growth in soft agarose.RT-PCR and Caspase-3 assay showed that HepG_2 cells treated with 25(?mol?L~(-1)) MSC for 24 and 48 hours,the expression of Cyclin D1 mRNA was down-regulated by 38% and 47%,while Caspase-3 activity was up-regulated by((39.61)?(6.65))%and((118.73)?(6.48))%.HepG_2 cells treated with 50(?mol?L~(-1)) MSC for 24 and 48 h,the expression of Cyclin D1 mRNA was down-regulated by 53% and 82%, whereas Caspase-3 activity was up-regulated by((80.66)?(9.31))% and((152.67)?(7.95))%.CONCLUSION: MSC can inhibit the growth of HepG_2 cells,and induce apoptosis and S phase arrest of HepG_2 cells.The phenotype alterations of HepG_2 cells might relate with inhibition of Cyclin D1 expression and Caspase-3 activity by MSC in the cells.

Objective To observe the lumbosacral plexus nerves by diffusion tensor tractography (DTT) and quantitatively evaluate them by using diffusion tensor imaging (DTI) in healthy volunteers.Methods A total of 60 healthy volunteers (30 males and 30 females) underwent DTI scanning.Mean FA values of the lumbosacral plexus nerves (both sides of lumbar roots L3 to S1,proximal and distal to the lumbar foraminal zone) were quantified.Differences among various segments of lumbar nerve roots were compared with ANOVA test and SNK test.Differences between two sides of the lumbar nerve roots at the same lumbar segment were compared with paired-samples t test.Differences between the proximal and the distal nerve to the the lumbar foraminal zone at the same lumbar segment were compared with paired-samples t test.The lumbosacral plexus nerve was visualized with tractography.Results (1) The lumbosacral plexus nerve was clearly visualized with tractography.(2) Mean FA values of the lumbar nerve roots L3 to S1 were as followings:proximal to the left lumbar foraminal zone 0.202 ± 0.021,0.201 ± 0.026,0.201 ± 0.027,0.191 ±0.016,distal to the left lumbar foraminal zone 0.222 ± 0.034,0.250 ± 0.028,0.203 ± 0.026,0.183 ± 0.020,proximal to the right lumbar foraminal zone 0.200 ± 0.023,0.202 ± 0.023,0.205 ± 0.027,0.191 ±0.017,distal to the right lumbar foraminal zone 0.225 ±0.032,0.247 ±0.027,0.205 ± 0.033,0.183 ±0.021.Mean FA values were significantly different between the proximal nerve to the distal nerve in lumbar nerve roots L3,L4,S1 (t =-9.114-2.366,P ＜ 0.05),but not significantly different in L5 (P ＞ 0.05).Differences were not found between the right and left side nerves at the same lumbar segment (P ＞ 0.05).(3) The whole length of the lumbar roots nerve L3 to S1 can be visualized clearly by using DTT.Conclusions Diffusion tensor imaging and tractography can show and provide quantitative information of human lumbosacral plexus nerves.DTI is a potential tool for the diagnosis of lumbosacral plexus nerve disease.