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Objective To investigate the role of Bmi1 on the migration of human umbilical vein endothelial cells (HUVECs) in response to low shear stress. Methods A parallel plate flow chamber system was used to generate low (0.5 Pa) or normal (1.5 Pa) laminar shear stress. HUVECs were isolated, cultured and exposed to flow for 12 hours. The mRNA and protein levels of Bmi1 were analyzed by real-time PCR and Western blot, respectively. Meanwhile, wound healing assay was performed to determine the migration of HUVECs. Bmi1 specific small interference RNA (siRNA) was used to silence Bmi1 gene. Results Low shear stress (0.5 Pa) significantly inhibited migration of HUVECs compared with normal shear stress (1.5 Pa). Similarly, compared with HUVECs exposed to normal shear stress, the expression of Bmi1 significantly increased in HUVECs exposed to low shear stress. Small interfering RNA knockdown of Bmi1 attenuated low shear stress-induced inhibition of HUVECs migration. Conclusions Low shear stress may inhibit the migration of HUVECs through up-regulation of Bmi1 expression. Knockdown of Bmi1 may reverse the HUVECs migration inhibited by low shear stress．
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OBJECTIVE: To study the combined effect of noise and hydrogen cyanide on noise-induced hearing loss( NIHL)in a metal electroplating enterprise. METHODS: The judgment sampling method was used to select 663 workers in a largescale metal electroplating enterprise as the study subjects. Among them,186 workers exposed to noise alone were designated as noise group; 138 workers exposed to hydrogen cyanide alone were designated as hydrogen cyanide group; and161 workers exposed to noise and hydrogen cyanide were designated as combined effect group,and 178 workers without exposure from occupational disease risk factors were designated as control group. Questionnaires survey and pure tone audiometry were used for analyzing the effects of combined noise and hydrogen cyanide exposure on NIHL. RESULTS: The hearing loss detection rate of the study subjects was 40. 4%. The hearing loss detection rates in the control group,noise group,hydrogen cyanide group,and combined effect group were 17. 4%,47. 8%,32. 6% and 64. 0%,respectively. The detection rate of hearing loss in the control group was lower than that in the other three groups( P < 0. 008). The NIHL detection rates in the combined effect group and the noise group were higher than that in the hydrogen cyanide group( P <0. 008). The hearing loss detection rate of the combined effect group was higher than that of the noise group and the hydrogen cyanide group( P < 0. 008). Ordinal multi-categorical logistic regression model results showed that after adjusting confounding factors such as age,length of service,gender,marital status,smoking,alcohol drinking,we found hydrogen cyanide exposure,noise exposure,and combined exposure to hydrogen cyanide and noise had effects on workers' hearing(P < 0. 05). The risk of hearing loss in workers exposed to noise and hydrogen cyanide was higher than that of workers exposed to noise alone or hydrogen cyanide alone. CONCLUSION: There is a combined effect of noise and hydrogen cyanide in this metal electroplating enterprise,which can increase the risk of NIHL in workers.
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Objective To investigate the effect of fluid shear stress (FSS) on the expression of B lymphoma MoMLV insertion region 1 (Bmi-1) in bone mesenchymal stem cells (BMSCs) and possible signal transduction mechanism.Methods BMSCs were isolated from SD rats and FSS at different magnitude (0.5,1.5,3.0 Pa)and under different time phase (1,2,6,24 h) were loaded by parallel-plate flow chamber system.The expression of Bmi-1 was measured by real-time RT-PCR at mRNA level and the levels of phosphorylated Akt (p-Akt)and extracellular signalregulated kinase 1/2 (p-ERK1/2) were detected by Western blotting.The signaling inhibitors,wortmannin (PI3K specific inhabitor) and PD98059 (ERK1/2 specific inhabitor),were used to investigate possible mechanical signal transduction pathway.Results Bmi-1mRNA expression increased when BMSCs were exposed to 1.5 Pa FSS for 1 h and reached the peak at 24 h.All FSS with different magnitude could increase Bmi-1 expression,especial at high FSS (3.0 Pa).Meanwhile,FSS resulted in a significant activation of p-Akt and p-ERK1/2 in BMSCs.After treated with wortmannin,the expression of Bmi-1 was inhibited prominently,however,PD98059,the expression of Bmi-1 did not change.Conclusions FSS can activate the expression of Bmi-1,the amount of Bmi-1 expression was closely related to the stimulating time and the magnitude of FSS,and Akt signal molecule plays an important role during the process.These findings provide significant references for studying the mechanical biological mechanisms of stem cell differentiation.
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This paper was designed to investigate the effect of laminar shear stress on matrix metalloproteinase -9 (MMP-9) expression in rat bone marrow-derived mesenchymal stem cells (MSCs), and the possible signal transduction mechanism involved. Rat bone marrow MSCs were isolated and cultured, then, exposed to laminar shear stress at indicated strengths such as low (5dyne/cm2), medium (15 dyne/cm2) and high (30 dyne/cm2) via parallel plate flow chamber. RT-PCR was used to analyze the expression of MMP-9. The signaling inhibitors such as Wortmannin (PI3K specific inhabitor), SB202190 (p38MAPK specific inhabitor), and PD98059 (ERK1/2 specific inhabitor) were used to investigate the possible mechanical signal transduction pathway. The results showed: (1) The expression of MMP-9 was weak in static state, however, MMP-9 expression increased when MSCs were exposed to 15 dyne/cm2 shear stress for 2 hours, and MMP-9 expression increased with the extension of stimulating time, and it reached the peak at 24 h; (2) MSCs were stimulated by shear stress for 2 hours at different strengths (5 dyne/cm2, 15 dyne/cm2, 30 dyne/cm2), and under all these conditions, the expression of MMP-9 increased, and reached the peak at 15 dyne/cm2; (3) After MSCs were pretreated by three kinds of signal pathway inhibitors, the expression of MMP-9 did not change obviously in Wortmannin group and PD98059 group, but it was significantly inhibited in SB202190 group. This study demonstrated that shear stress could induce the expression of MMP-9 in rat bone marrow-derived mesenchymal stem cells; the amount of MMP-9 expression was closely related to stimulating time and the strengths of shear stress; and p38MAPK signal pathway played a critical role during the process.
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Animals , Rats , Bone Marrow Cells , Cell Biology , Metabolism , Cells, Cultured , Matrix Metalloproteinase 9 , Genetics , Metabolism , Mesenchymal Stem Cells , Cell Biology , Metabolism , Signal Transduction , Stress, MechanicalABSTRACT
Introducing the PBL teaching mode in regional anatomy teaching accords with the need of 21centuries social development for the highquality medical science personnel training and the regional anatomy course characteristic, and is beneficial to the students’ changing their study concept and raising their learning ability. It is also an effective way for allaround quality education.
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AIM: To evaluate the role of human angiotensin Ⅱ(AngⅡ) type Ⅰ receptor (AT1R) antisense cDNA (ahAT1) on migration of cultured artery smooth muscle cells (VSMCs). METHODS: Two recombinant adenoviral vectors, Ad/CMV. ahAT1 containing full length antisense cDNA targeting to human AT1R mRNA, and Ad/CMV.LacZ containing LacZ called report gene, were constructed by orientation clone technology and homologous recombination, and then were used to transfect VSMCs in vitro. AT1R expression detected by RT-PCR and immunohistochemistry, and migration of VSMCs measured by Boyden's Chamer methods, were compared between transfected and non- transfected VSMCs. RESULTS: Forty-eight hours after Ad/CMV. ahAT1 transfection, the level of AT1R mRNA decreased markedly (50% of control group), and AT1R protein expression was significantly less (P