OBJECTIVE To reveal the biological effects and effective dosage in radiotherapy model which applies high single-dose irradiation by animal experiment. METHODS We inoculated subcutaneouly human pancreatic carcinoma cel...OBJECTIVE To reveal the biological effects and effective dosage in radiotherapy model which applies high single-dose irradiation by animal experiment. METHODS We inoculated subcutaneouly human pancreatic carcinoma cell line （MIA PaCa-2） in the lateral of the right lower extremity of the athymic mouse to grow transplantation tumor. While the median diameter of transplantation tumor reached 10 mm approximately, the animals were randomly divided into 7 groups （6 animals per group） and irradiation by different dose in one fixed with consciousness for fraction （0, 2, 5, 10, 17, 25, 35 Gy）. All were kept on to be bred for observation of the change in gross tumor volume, calculation of delayed growth time and delayed growth curve. RESULTS With increased dose per fraction, cutaneous reaction on the neoplasma surface of the animal, which was mainly moist yellow effusion was more and more severe. When dosage is less than 10 Gy, all animals showed similar effects, that＇s the delayed tumor growth was not obvious. Tumors receiving more than 10 Gy in one fraction showed very good biological effect and the delayed tumor growth was obviously related to dosage. The difference in delayed tumor growth between the 2 groups was statistically significant. The delayed tumor growth time in 10, 17, 25 Gy group was respectively 3 weeks, 6 weeks and more. CONCLUSION The biological effect of the model which applies high single-dose irradiation （more than 10 Gy in one fraction） was very good. The effect of delayed tumor growth was obviously related to the dosage after transplantation tumor was radiated. Because of its higher dose per fraction and biological effects, the model of high single-dose irradiation can get better clinical effects.展开更多
A differential-algebraic prey--predator model with time delay and Allee effect on the growth of the prey population is investigated. Using differential-algebraic system theory, we transform the prey predator model int...A differential-algebraic prey--predator model with time delay and Allee effect on the growth of the prey population is investigated. Using differential-algebraic system theory, we transform the prey predator model into its normal form and study its dynamics in terms of local analysis and Hopf bifurcation. By analyzing the associated characteristic equation, it is observed that the model undergoes a Hopf bifurcation at some critical value of time delay. In particular, we study the direction of Hopf bifurcation and the stability of bifurcated periodic solutions, and an explicit algorithm is given by applying the normal form theory and the center manifold reduction for functional differential equations. Finally, numerical simulations supporting the theoretical analysis are also included.展开更多
文摘OBJECTIVE To reveal the biological effects and effective dosage in radiotherapy model which applies high single-dose irradiation by animal experiment. METHODS We inoculated subcutaneouly human pancreatic carcinoma cell line （MIA PaCa-2） in the lateral of the right lower extremity of the athymic mouse to grow transplantation tumor. While the median diameter of transplantation tumor reached 10 mm approximately, the animals were randomly divided into 7 groups （6 animals per group） and irradiation by different dose in one fixed with consciousness for fraction （0, 2, 5, 10, 17, 25, 35 Gy）. All were kept on to be bred for observation of the change in gross tumor volume, calculation of delayed growth time and delayed growth curve. RESULTS With increased dose per fraction, cutaneous reaction on the neoplasma surface of the animal, which was mainly moist yellow effusion was more and more severe. When dosage is less than 10 Gy, all animals showed similar effects, that＇s the delayed tumor growth was not obvious. Tumors receiving more than 10 Gy in one fraction showed very good biological effect and the delayed tumor growth was obviously related to dosage. The difference in delayed tumor growth between the 2 groups was statistically significant. The delayed tumor growth time in 10, 17, 25 Gy group was respectively 3 weeks, 6 weeks and more. CONCLUSION The biological effect of the model which applies high single-dose irradiation （more than 10 Gy in one fraction） was very good. The effect of delayed tumor growth was obviously related to the dosage after transplantation tumor was radiated. Because of its higher dose per fraction and biological effects, the model of high single-dose irradiation can get better clinical effects.
基金This work was supported by National Science Foundation of China 61273008 and 61203001, Doctor Startup Fund of Liaoning Province （20131026）, Fundamental Research Funds for the Central University （N140504005） and China Scholarship Council. The authors gratefully thank referees for their valuable suggestions.
文摘A differential-algebraic prey--predator model with time delay and Allee effect on the growth of the prey population is investigated. Using differential-algebraic system theory, we transform the prey predator model into its normal form and study its dynamics in terms of local analysis and Hopf bifurcation. By analyzing the associated characteristic equation, it is observed that the model undergoes a Hopf bifurcation at some critical value of time delay. In particular, we study the direction of Hopf bifurcation and the stability of bifurcated periodic solutions, and an explicit algorithm is given by applying the normal form theory and the center manifold reduction for functional differential equations. Finally, numerical simulations supporting the theoretical analysis are also included.
