Efficacy of mandibular molar distalization by clear aligner treatment / 中南大学学报(医学版)

OBJECTIVES@#At present, the research on clear aligner of molar distalization mainly focuses on the upper jaw, while the research on mandibular molars is few.This study aims to evaluate the therapeutic effect of mandibular molars distalization with clear aligner via cone beam CT (CBCT) and Dolphin software.@*METHODS@#Twenty cases of mandibular molars with clear aligner were included according to the inclusion and exclusion criteria. CBCT was taken before treatment (T0) and when the first molar was moved in place (T1). Dolphin software was used to measure the effectiveness of molar distalization. Three-dimensional changes in direction and the impact on the incisors and facial soft and hard tissues were evaluated.@*RESULTS@#The effective rates of crown and root distalization of the second and first mandibular molars were 74%, 49%, and 71%, 47%, respectively. The second and first molars were both the distal buccal cusp with the largest distalization [(2.15 ± 0.91) mm and (1.85±1.09) mm], respectively, with significant difference between the T0 and T1 (@*CONCLUSIONS@#Clear aligner can effectively move mandibular molars farther, the crown is more effective than the root, and it is tilted. The second mandibular molar is more effective than the first mandibular molar in its distant displacement and three-dimensional changes. Molar distalization causes minor changes in mandibular incisors and facial soft and hard tissues.

Isolation and in vitro culture of neonatal rats liver cells / 中国组织工程研究

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.

Study on Evaluation Method of Scaffold for the Use of Liver Tissue Engineering / 医疗卫生装备

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.

Influence of stretch strain and pressure on expression of osteoblasts' FOS protein / 生物医学工程学杂志

Uniaxial stretch strain and compressive pressure of 2 atm were applied to rat's osteoblasts, and then immunohistochemistrical staining was used to detect the expression of osteoblasts' c-fos gene. The experiment result indicated the osteoblasts' FOS proteins increased prominently, and the FOS proteins concentrated in nucleolus after having endured two different kinds of loadings. It is very important to prompt stress and strain in promoting osteoblast proliferation.

Effects of recombinant bovine basic fibroblast growth factor on osteoblast's growth and c-fos expression / 生物医学工程学杂志

Rat's osteoblasts cultured in vitro were stimulated by recombinant bovine basic fibroblast growth factor(rb-bFGF). After 1-2 days, the osteoblast grew long protuberance, the numbers of osteoblasts were greater than the control groups', the vitality of osteoblasts was better than that of control groups. After 1 hour, the expression of c-fos in osteoblast increased when compared with that in the control group. After the osteoblasts having been stimulated for 1-2 days, the expression of c-fos increased more conspicuously. These results show that bFGF can boost the osteoblast to grow and proliferate and can enhance the expression of c-fos gene. The increase of c-fos gene's expression may be an important step in the signal transformation process of all kinds of stimulation boosting osteoblast to proliferate.

Study on inducing differentiation of mouse embryonic stem cells into cardiomyocytes in vitro / 中国病理生理杂志

AIM: To set up a method of inducing mouse embryonic stem cells (mESC) to differentiate into cardiomyocyte after treatment with 5-azacytidine. METHODS: Cytotoxicity of 5-azacytidine was measured by MTT assay. Treatment of mESC with conditioned culture mediums, which were composed of 5-azacytidine alone or combined with retinoic acid, induced the cell differentiation to cardiomyocytes. The cells induced were identified by detecting the expression of cardiac proteins (myosin, desmin, ?-actin and ?-actinin). Gene MLC-2v, a specific gene of ventricular-like cardiomyocyte, was also detected by RT-PCR. RESULTS: The non-cytotoxic dose of 5-azacytidine was 8 ?mol/L, which was able to induce mESC to differentiate into cardiac syncytiums. Cells induced expressed many cardiac proteins and MLC-2v mRNA. However, combined with retinoic acid inhibited mESC differentiation into cardiomyocyte. CONCLUSION: 5-azacytidine is able to promote mESC differentiation into cardiomyocytes. A method of inducing mESC to differentiate into cardiomyocytes in vitro has been established.