RESUMO
Objective To investigate the correlation between invasion ability and cytoskeleton remodeling of hepatocarcinoma cell by atomic force microscopy (AFM) and to explore mechanical properties during genesis,development and invasion of hepatocellular carcinoma (HCC).Methods Four HCC cell lines (MHCC-97H,MHCC-97L,SMMC-7721 ,Huh-7 )with different invasive ability were studied.Mechanical parameter (Young′s modulus)was measured by AFM.The pattern of cytoskeleton remodeling of HCC cell lines with different invasive ability was detected by immunofluorescent staining. The difference of cell invasive ability was tested by cell scratch experiment in other to verify mechanical data.Kruskal-Wallis H test was used to compare the differences between groups.Results The results of AFM indicated that Young′s modulus of cytoplasma area and nucleus area decreased gradually as cell invasion ability increased (χ2 =472.78,622.43,both P <0.01).According to invasive ability from low to high,Young′s modulus of cell cytoplasm area of Huh-7,SMMC-7721 ,MHCC-97L and MHCC-97H were 1 602.43 (845 .48,3 317.25)Pa,1 055 .28 (367.48,2 280.77)Pa,1 026.78 (369.20,2 019.96)Pa and 503.12 (366.11 ,700.31)Pa,respectively.Young′s modulus of cell nucleus area of Huh-7,SMMC-7721 ,MHCC-97L and MHCC-97H were 2 823.98 (1 262.78,4 440.07 )Pa,1 313.43 (590.71 , 2 678.62)Pa,1 285 .17 (583.29,1 961 .19)Pa and 655 .57 (441 .29,943.39)Pa,respectively.The results of immunofluorescent staining showed that the stronger the cell invasive ability,the worse cytoskeletal integrity and more irregular cell microfilament distribution. In cell scratch assay, the migration rate of MHCC-97H was 46.67% in 24 h and 86.47% in 48 h,that of MHCC-97L was 45 .70%in 24 h and 82.86% in 48 h,that of SMMC-7721 was 39.41 % in 24 h and 79.85 % in 48 h and that of Huh-7 was 34.60% in 24 h and 72.09% in 48 h,which showed that the cell migration orderly in creased as the cell invasion ability increased.Conclusions It seemed that HCC with higher invasive ability had lower Young′s modulus,softer cell,stronger deformability,worse cytoskeleton integrity and more irregular cell structure,and vice versa.
RESUMO
<p><b>OBJECTIVE</b>To investigate the effect of en-masse retraction of maxillary anterior teeth by rocking-chair archwire (RCA) in sliding mechanics.</p><p><b>METHODS</b>The three dimensional finite element model of maxillary teeth was created based on spiral CT data of a patient by ANSYS software. The forces on each tooth and the torques on the six center of resistance (CR) of the anterior teeth induced by the deformation of RCA with different depth and anterior retraction hook (ARH) with different height were calculated when retracted from a mini-implant between the first molar and the second premolar. The movements of anterior teeth were observed combining different depth of RCA with different height of ARH.</p><p><b>RESULTS</b>The clockwise torque in sliding mechanics to realize en-masse retraction of the anterior teeth could be counterbalanced by RCA of certain depth. The combination of 7.2 mm ARH and 2 mm RCA can be used to intrude and retract maxillary anterior teeth under the condition of applying mini-implant.</p><p><b>CONCLUSION</b>The excessive retraction that usually exists in traditional treatments can be avoided by RCA in sliding mechanics and intrusion and torque control during anterior segment retraction can also be achieved by this method.</p>