Objective:The aim of this study was to discuss the effect of pre-low-dose X-ray radiation on P53,Bcl-2 and apoptosis of HepG2 cells in tumor-bearing nude mouse,and further explore the mechanism of low doses radiation....Objective:The aim of this study was to discuss the effect of pre-low-dose X-ray radiation on P53,Bcl-2 and apoptosis of HepG2 cells in tumor-bearing nude mouse,and further explore the mechanism of low doses radiation.Methods:HepG2 cells were implanted subcutaneously into nude mice.14 days after the implanting,these mice were divided into 6 groups randomly,S group (sham-irradiation 0 cGy),D1 group (7.5 cGy,dosage rate=7.5 cGy/min),D2 group,(200 cGy,dosage rate=100 cGy/min),D1 + 2 h + D2 group,D1 + 6 h + D2 group and D1 + 12 h + D2 group.Tumor-bearing mice in each experimental group were executed at 24 h after the last irradiation.P53 and Bcl-2 were detected by immunohistochemical staining,the tumor tissues apoptosis were detected in site (Tunel).Results:Each combined exposure groups (D1 + 2 h + D2 group,D1 + 6 h + D2 group and D1 + 12 h + D2 group) compared with the D2 group,the percentages of positive P53 and Bcl-2 were decreased obviously,and the apoptotic indexs were increased (P < 0.01).Conclusion:Pre-low-dose radiation combined with the conventional radiation can increase the apoptosis of tumor tissues by decreasing the expression of P53 and Bcl-2,it can enhance the anti-tumor effect of conventional radiation,and it can have actual clinical significance on supporting radiotherapy.展开更多
Objective： We aimed to study the effect and mechanism of low-dose radiation （LDR） on adaptive response of gastric cancer cell. Methods： SGC7901 cells were cultured in vitro, and divided into 4 groups： control gro...Objective： We aimed to study the effect and mechanism of low-dose radiation （LDR） on adaptive response of gastric cancer cell. Methods： SGC7901 cells were cultured in vitro, and divided into 4 groups： control group （DO group）, low-dose radiation group （D1 group, 75 mGy）, high-dose radiation group （D2 group, 2 Gy）, low-dose plus high-dose radiation group （D1 ＋ D2 group, 75 mGy ＋ 2 Gy, the interval of low and high-close radiation being 8 h）. Cell inhibition rate was detected by cytometry and CCK8 method; the proportion of cell cycle at different times after irradiation was determined by using a flow cytometry. The ATM mRNA levels were detected by using quantitative real-time reverse transcription polymerase chain reaction （RT-PCR）. Results： There was no significant different between groups DO and D1, groups D2 and D1 ＋ D2 cell inhibition rate （P 〉 0.05）. There was a significant increase G2/M arrest in groups D2 and D1 ＋ D2 than groups DO and D1 after 6 h of radiation and did not recover at 48 h （P 〈 0.05）. The ATM mRNA expression of group D2 and D1 ＋ D2 increased highly than that of group DO and D1 （P 〈 0.05）. However, differences between group D2 and D1 ＋ D2, group DO and D1 were not statistical significant （P 〉 0.05）. Conclusion： LDR cannot induce adaptive response in SGC7901 cells in vitro, which may be associated the regulation of cell cycle, and its ATM mRNA expression cannot be affected by 75 mGy X-ray radiation.展开更多
Poly（L-lactic acid） （PLLA） and poly（e-caprolactone） （PCL） have been receiving much attention lately due to their biodegradability in human body as well as in the soil, also due to their biocompatibility, envir...Poly（L-lactic acid） （PLLA） and poly（e-caprolactone） （PCL） have been receiving much attention lately due to their biodegradability in human body as well as in the soil, also due to their biocompatibility, environmentally friendly characteristics and non-toxicity. Morphology of biodegradable polymers affects the rate of their biodegradation. A polymer that has high degree of crystallinity will degrade at a slower rate due to the inherent increased stability. PCL homopolymer crosslinking degree increases with increasing doses of high energy radiation. On the other hand, the irradiation ofPLLA homopolymer promotes mainly chain-scissions at doses below 250 kGy. In the present work, twin screw extruded films of PLLA and PCL biodegradable homopolymers and 50：50 （w：w） blend were electron beam irradiated using electron beam accelerator Dynamitron （E = 1.5 MeV） from Radiation Dynamics, Inc. at doses in the range of 50 kGy to 103 kGy in order to evaluate the effect of electron beam radiation. Wide-angle X-ray diffraction （WAXD） patterns of non irradiated and irradiated samples were obtained using a diffractometer Rigaku Denki Co. Ltd., Multiflex model; and Fourier transform infrared spectroscopy （FTIR） spectra was obtained using a NICOLET 4700, attenuated total reflectance （ATR） technique. By WAXD patterns of as extruded non irradiated and irradiated PLLA it was verified broad diffusion peaks corresponding to amorphous polymer. There was a slight increase of the mean crystallite size of PCL homopolymer with increasing radiation dose. PCL crystalline index （CI） decreased with radiation dose above 500 kGy. But then, PLLA CI increased with radiation dose above 750 kGy. From another point of view, PLLA presence on the 50：50 blend did not interfere on the observed mean crystallite size increase up to 250 kGy. From 500 kGy to 103 kGy the crystallite size of PCL was a little bigger in the blend than the homopolymer. In contrast, FTIR results have shown that this technique was not sensitive enough to observe the degradation promoted by ionizing radiation of the studied homopolymers and blends, and neither on the miscibility of the blends.展开更多
文摘Objective:The aim of this study was to discuss the effect of pre-low-dose X-ray radiation on P53,Bcl-2 and apoptosis of HepG2 cells in tumor-bearing nude mouse,and further explore the mechanism of low doses radiation.Methods:HepG2 cells were implanted subcutaneously into nude mice.14 days after the implanting,these mice were divided into 6 groups randomly,S group (sham-irradiation 0 cGy),D1 group (7.5 cGy,dosage rate=7.5 cGy/min),D2 group,(200 cGy,dosage rate=100 cGy/min),D1 + 2 h + D2 group,D1 + 6 h + D2 group and D1 + 12 h + D2 group.Tumor-bearing mice in each experimental group were executed at 24 h after the last irradiation.P53 and Bcl-2 were detected by immunohistochemical staining,the tumor tissues apoptosis were detected in site (Tunel).Results:Each combined exposure groups (D1 + 2 h + D2 group,D1 + 6 h + D2 group and D1 + 12 h + D2 group) compared with the D2 group,the percentages of positive P53 and Bcl-2 were decreased obviously,and the apoptotic indexs were increased (P < 0.01).Conclusion:Pre-low-dose radiation combined with the conventional radiation can increase the apoptosis of tumor tissues by decreasing the expression of P53 and Bcl-2,it can enhance the anti-tumor effect of conventional radiation,and it can have actual clinical significance on supporting radiotherapy.
文摘Objective： We aimed to study the effect and mechanism of low-dose radiation （LDR） on adaptive response of gastric cancer cell. Methods： SGC7901 cells were cultured in vitro, and divided into 4 groups： control group （DO group）, low-dose radiation group （D1 group, 75 mGy）, high-dose radiation group （D2 group, 2 Gy）, low-dose plus high-dose radiation group （D1 ＋ D2 group, 75 mGy ＋ 2 Gy, the interval of low and high-close radiation being 8 h）. Cell inhibition rate was detected by cytometry and CCK8 method; the proportion of cell cycle at different times after irradiation was determined by using a flow cytometry. The ATM mRNA levels were detected by using quantitative real-time reverse transcription polymerase chain reaction （RT-PCR）. Results： There was no significant different between groups DO and D1, groups D2 and D1 ＋ D2 cell inhibition rate （P 〉 0.05）. There was a significant increase G2/M arrest in groups D2 and D1 ＋ D2 than groups DO and D1 after 6 h of radiation and did not recover at 48 h （P 〈 0.05）. The ATM mRNA expression of group D2 and D1 ＋ D2 increased highly than that of group DO and D1 （P 〈 0.05）. However, differences between group D2 and D1 ＋ D2, group DO and D1 were not statistical significant （P 〉 0.05）. Conclusion： LDR cannot induce adaptive response in SGC7901 cells in vitro, which may be associated the regulation of cell cycle, and its ATM mRNA expression cannot be affected by 75 mGy X-ray radiation.
文摘Poly（L-lactic acid） （PLLA） and poly（e-caprolactone） （PCL） have been receiving much attention lately due to their biodegradability in human body as well as in the soil, also due to their biocompatibility, environmentally friendly characteristics and non-toxicity. Morphology of biodegradable polymers affects the rate of their biodegradation. A polymer that has high degree of crystallinity will degrade at a slower rate due to the inherent increased stability. PCL homopolymer crosslinking degree increases with increasing doses of high energy radiation. On the other hand, the irradiation ofPLLA homopolymer promotes mainly chain-scissions at doses below 250 kGy. In the present work, twin screw extruded films of PLLA and PCL biodegradable homopolymers and 50：50 （w：w） blend were electron beam irradiated using electron beam accelerator Dynamitron （E = 1.5 MeV） from Radiation Dynamics, Inc. at doses in the range of 50 kGy to 103 kGy in order to evaluate the effect of electron beam radiation. Wide-angle X-ray diffraction （WAXD） patterns of non irradiated and irradiated samples were obtained using a diffractometer Rigaku Denki Co. Ltd., Multiflex model; and Fourier transform infrared spectroscopy （FTIR） spectra was obtained using a NICOLET 4700, attenuated total reflectance （ATR） technique. By WAXD patterns of as extruded non irradiated and irradiated PLLA it was verified broad diffusion peaks corresponding to amorphous polymer. There was a slight increase of the mean crystallite size of PCL homopolymer with increasing radiation dose. PCL crystalline index （CI） decreased with radiation dose above 500 kGy. But then, PLLA CI increased with radiation dose above 750 kGy. From another point of view, PLLA presence on the 50：50 blend did not interfere on the observed mean crystallite size increase up to 250 kGy. From 500 kGy to 103 kGy the crystallite size of PCL was a little bigger in the blend than the homopolymer. In contrast, FTIR results have shown that this technique was not sensitive enough to observe the degradation promoted by ionizing radiation of the studied homopolymers and blends, and neither on the miscibility of the blends.
