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Objective@#To detect the alterations of telomerase activity and the expression for oxidative stress responsive genes related with senescence during cellular replicative senescence and hydrogen peroxide-induced premature senescence in human embryonic lung fibroblasts (HELFs) in vitro.@*Methods@#The HELFs were divided into young cells (22 population doubling levels, 22PDL) , mid-aged cells (35PDL) and replicative senes-cent cells (49PDL) and premature senescent cells induced by H2O2(premature senescence, PS). The telomerase activity was detected by ELISA assay during cellular replicative and premature senescence. The mRNA level of oxidative stress responsive genes related with senescence for Foxo1, Foxo3, Pdx1, apoA-I and MMP1 was per-formed by RT-Q-PCR separately.@*Results@#The mRNA level for Foxo1, Foxo3, apoA-I and Pdx1 was decreased separately during cellular replicative senescence compared to that in the young-stage cells with statistical signifi-cance (P<0.05). The expression of MMP1 was up-regulated 5.1-fold obviously (P<0.05). In premature senes-cence, the mRNA level was only decreased for Foxo1, Foxo3 and apoA-I, but up-regulated 2.3-fold and 6.2-fold for Pdx1 and MMP1 respcetively vs 22PDL significantly (P<0.05). The telomerase activity in young cells was not detected, and it increased in mid-aged cells and replicative senescence stages during cellular replicative se-nescence as compared to 22PDL with statistical significance (P<0.05). The telomerase activity in premature se-nescence was highly active.@*Conclusion@#The expression for genes related with senescence has differences be-tween replicative and premature senescence and hydrogen peroxide modifies their expression levels. The telomer-ase activity has been going up with increased PDLs.
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Objective To analyze the direct and indirect effects of influencing factors on suicide ideation among college students based on the structural equation model. Methods 1505 college students were investigated with ASLEC, Simplified Coping Style Questionnaire, SSRS, QSA and BDI. Results Incidence rate of college students' suicidal ideations during the past year was 6.67%. The goodness of fit for the structural equation model was satisfactory and 3 major indices( x2/df = 2.23, GFI = 0. 982, RMSEA = 0. 029 ) had met corresponding requirements. The depression was directly influencing factor on suicide ideation, while four factors including passive coping style, social support, positive coping style and suicide attitude, had indirect impacts. Negative life event not only directly affected suicide ideation, but also had indirect effects. According to the percentages of their contribution, the risk factors were ranked as follows:depression (41.08%), negativity life event (35.35%) and passive coping style (6.05%). Similarly, the top protective factor was: social support ( 11.94% ), followed by positive coping style (4.94%) and suicide attitude (0.63%). Conclusion Depression is an important risk factor of suicide,and has a direct impact. So, not only strengthen the mental health of college students, but also train students to face up the difficulties with a positive style, and make the college students get social supports sufficiently.
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AIM: To construct eukaryotic expression vector of human vascular endothelial growth factor (VEGF) gene, and to explore the effects of VEGF gene on proliferation and chemosensitivity of leukemia cells. METHODS: The recombinant eukaryotic express plasmid pEGFP-C1-hVEGF_(165) was constructed with conventional gene engineering methods. The pEGFP-C1-hVEGF_165 was transfected into leukemia cell K562. The proliferation of the recombinant eukaryotic expression plasmid was analyzed by CCK8 method. The level of VEGF mRNA was detected by reverse transcription and quantitative polymerase chain reaction (RT-PCR). The expression level of VEGF protein was determined by ELISA in cell culture medium and cells. The cell cycle was detected by flow cytometry. RESULTS: VEGF_(165) eukaryotic expression vector was successfully constructed, confirmed by enzyme digestion and sequencing. Compared with the K562 cells transfected pEGFP-C1, the K562 cells transfected with pEGFP-C1-hVEGF_(165) grew faster and expressions of VEGF mRNA and protein increased significantly. In addition, K562 cells transfected with pEGFP-C1-hVEGF_(165) had relatively higher cell survival rate to chemotherapy drugs homoharringtonine(HHT) and fluorouracil(FU). CONCLUSION: VEGF_(165) eukaryotic expression vector increases the level of VEGF mRNA and protein expression, accordingly promotes the proliferation of leukemia cells and decreases the sensitivity of leukemia cells to HHT and FU.
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Objective Nine VEGF siRNAs were designed and their efficiencys were evaluated for introducing new and effective design rules of siRNA.Methods Nine VEGF siRNA sequences with nineteen nucleic acids were designed.After construction in vitro,VEGF siRNAs were transferred into neuroglioma cells by lipofectamine.The level of VEGF protein in the media was determined by ELISA 48 hours after transferring.The relationship between the characteristics of VEGF siRNA and its' interfering effect were analyzed.Results A quantitative parameter called H-b index were used to characterize the secondary structure of VEGF mRNA.A low value of the H-b index would mean that the structure of mRNA is loose,in which the nucleotides of the targeting region are likely to be accessible by siRNA and the effects are better.The experiments showed a negative correlation between the suppression of VEGF protein expression and H-b index(r=-0.498).The H-b indexs of siRNAs targeting VEGF mRNA 386～406 and 401～421 position were less,however the effects of suppression were better.The siRNAs conferred a strong RNAi activity with A residue at position 6 and A/U residues at position 19 of sense strand of siRNAs.Thethermodynamic properties of siRNA play a critical role in the transferring effects.The lower average of internal stability values for positions 9～14 of the antisense strand is facilitating the interfering effect.The lower binding energy is the more stable incorporation between antisense strand of siRNA and mRNA present,the more favorable is for RISC cleaving mRNA.Conclusions The sequences of VEGF siRNA have been designed successfully and effectively inhibited the expression of VEGF protein.
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Objective To study the status and risk factors for falling down in elderly people in rural areas, and to provide evidences for preventions. Methods A total of 1 003 farmers aged 60 years old and over were surveyed to study the falls occurred during the previous 12 months before March 2001 in the elderly in a town of Laizhou City by cluster sampling method. Results The average incidence of falling down was 22.6%, 15.9% for men and 28.4% for women, respectively. The risk factors of falls included gender, age, single-living, falling history in the previous year, at least combined two kinds of chronic diseases, manifesting at least two symptoms, gait abnormalities, as well as complaining poor physical status and poorer general conditions than the previous year. Less social actions was negatively associated with the falls. Conclusions The falling in the elderly walkers results from an outcome of combination of multifactors. Since the complex pathogenesis, it should be prevented by a combination of several methods.
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Objective To investigate the relationship between gliosis, synaptic reorganization and the mechanism of chronic temporal lobe epilepsy induced by kainic acid. Methods The mossy fibers sprouting, synaptic reorganization and gliosis were observed by Neo-Timm staining and immunohistochemical staining respectively. Results The injected (ipslateral) side was injured predominantly in the CA 3 subfield and hilus, whereas the CA 1 subfield was injured mildlyThe contralateral side showed pathological changes mainly in the CA 1 subfield and hilus, and moderately in the CA 3 subfieldThe longer the rats survived, the more obvious changes were observed in the hippocampuses. Conclusion The injection of kainic acid in hippocampus can cause neuronal loss, reactive gliosis and plasticity of neurons, probably form the abnormal neuronal discharge circuit, finally induce the seizures
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AIM: To investigate the mutagenicity of cadmium and zinc and the effect of zinc on the mutagenicity of cadmium. METHODS: The frequency of sister chromatid exchange (SCE) induced by cadmium, zinc and the combination of cadmium and zinc were observed in cultured human lymphocytes. RESULTS: Cadmium induced the increase in frequency of SCE in human lymphocytes from the concentration 1?10~(-8) mol/L to 1?10~(-6) mol/L, but zinc had a negative result. Zinc reduced the frequency of SCE induced by cadmium at the concentration from 1?10~(-6) mol/L to 1?10~(-4) mol/L and a relationship between dose and effect was also observed. CONCLUSION: Zinc inhibits the mutagenicity of cadmium in cultured human lymphocytes.
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AIM: To determine the inhibition of VEGF small interfering RNA (siRNA) on expression of VEGF protein and SMMC 7721 cell growth. METHODS: Nine VEGFsiRNA sequences with nineteen nucleotides were designed under the assistance of computer. The inhibitory effect of VEGFsiRNA was analyzed by CCK8. The protein level of VEGF in the media was determined by ELISA. The change of cell cycle was detected by flow cytometry. RESULTS: All the VEGFsiRNA were capable of inhibiting the proliferation of SMMC 7721 cells significantly compared with control and lipofectamine control, while the inhibitory effects of VEGFsiRNA2, VEGFsiRNA4, VEGFsiRNA6, VEGFsiRNA7, VEGFsiRNA8 and VEGFsiRNA9 were better than that of antisense oligodeoxynucleotide. All the VEGFsiRNA reduced the expression of VEGF protein. The effect of VEGFsiRNA7 and VEGFsiRNA2 were the best with the inhibitory rates of 52.65% and 50.43%, respectively. VEGFsiRNAs induced the S arrest in SMMC 7721 cells. The signs of apoptosis in SMMC 7721 cells induced by VEGFsiRNA were not observed. CONCLUSION: VEGFsiRNA sequences were designed and synthesized successfully. VEGFsiRNA effectively inhibited the proliferation of SMMC 7721 cells and reduced the level of VEGF protein.