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1.
Med Sci Monit ; 21: 2397-405, 2015 Aug 15.
Article in English | MEDLINE | ID: mdl-26280694

ABSTRACT

BACKGROUND: In this study, we aimed to establish the rabbit VX2 limb tumor model, and then prepare a "necrotic zone" as a safe margin by volumetric modulated arc therapy and simultaneous integrated boost (VMAT-SIB) technique applied in the areas where the tumor is located adjacent to the bone (GTVboost area). MATERIAL AND METHODS: Rabbits in the control group (n=10) were not treated, while those in the test group (n=10) were treated with the SIB schedule delivering a dose of 40Gy, 35Gy, 30Gy, and 25Gy to the GTVboost, GTV (gross tumor volume), CTV (clinical target volume), and PTV (planning target volume) in 10 fractions. Magnetic resonance diffusion-weighted imaging (MRDWI), 3-dimensional power Doppler angiography (3D-PDA), and histological changes were observed after radiotherapy. RESULTS: After radiotherapy, the two groups showed a significant difference in the GTVboost area. In the test group, the tumor necrosis showed a significantly low signal in DWI and high signal in apparent diffusion coefficient (ADC) maps. The 3D-PDA observation showed that tumor vascular structures decreased significantly. Histological analysis demonstrated that a necrotic zone could be generated in the GTVboost area, and microscopic examination observed cell necrosis and fibroplasia. CONCLUSIONS: This studies demonstrated the feasibility of using VMAT-SIB technique in the rabbit VX2 limb tumor model. The formation of a necrotic zone can be effectively defined as safe margin in the GTVboost area. showing potential clinical applicability.


Subject(s)
Radiotherapy, Intensity-Modulated/methods , Sarcoma, Experimental/radiotherapy , Soft Tissue Neoplasms/radiotherapy , Angiography , Animals , Diffusion Magnetic Resonance Imaging , Extremities , Imaging, Three-Dimensional , Magnetic Resonance Imaging , Male , Necrosis , Rabbits , Radiotherapy Dosage , Sarcoma, Experimental/blood supply , Sarcoma, Experimental/pathology , Soft Tissue Neoplasms/blood supply , Soft Tissue Neoplasms/pathology , Ultrasonography, Doppler
2.
Ying Yong Sheng Tai Xue Bao ; 19(11): 2388-93, 2008 Nov.
Article in Chinese | MEDLINE | ID: mdl-19238837

ABSTRACT

A rain-proof pool culture experiment was conducted to study the effects of nitrogen (N) application rate and post-anthesis soil moisture content on the flag leaf senescence and kernel weight of wheat. The results indicated that in all N fertilization treatments, the flag leaf SPAD value, soluble protein content, SOD and CAT activities, and photosynthetic rate decreased in the order of 60% -70% > 80%-90% >40%-50% post-anthesis soil moisture content, while the MDA content decreased in reverse order, suggesting that over high or low post-anthesis soil moisture content could cause the early senescence of flag leaves, impact grain filling, and decrease kernel weight. Under the same post-anthesis soil moisture content, the SPAD value, soluble protein content, SOD and CAT activity, and photosynthetic rate increased, while the MDA content decreased with increasing N application rate, indicating that increased N fertilization could postpone the senescence of wheat flag leaves. However, over N application was not favorable to the increase of kernel weight, especially under the condition of post-anthesis soil moisture deficiency. It was concluded that appropriate N application and post-anthesis soil moisture content control could postpone the plant senescence and increase the kernel weight of wheat.


Subject(s)
Fertilizers , Nitrogen/analysis , Soil/analysis , Triticum/growth & development , Water/analysis , Biomass , Nitrogen/metabolism , Plant Leaves/physiology , Proteins/analysis , Triticum/metabolism , Triticum/physiology , Water/metabolism
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