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Objective: To evaluate the application of computational fluid dynamics (CFD) on a patient-specific hemodynamic model of aortic arch., Methods: The original Dicom format image data of a patient were acquired by computed tomographic angiography (CTA). A 3-dimensional (3D) model based on CFD was constructed through the right amount of boundary conditions and hemodynamic parameters related with flow velocity, shear force and wall stress on lumen were analyzed accordingly., Results: The 3D model based on CFD could reflect the characteristic of flow velocity, shear force and wall stress on lumen in vitro. (1) The distributions of hemodynamic variables during cardiac cycle were spatiotemporally different. The unidirectional high-speed systolic current was replaced by diastolic eddy current and reversed flow. The distribution of flow velocity and shear stress gradually increased from outer wall of aortic artery to inner wall under the influences of such anatomical factors as vascular branching and distortions of descending aorta; (2) the magnitude and volatility of wall stress in ascending aorta were greater than those of aortic arch and descending aorta, but the least results were at the lateral wall of descending aorta area. In addition, the wall stress of external wall was higher than the lateral wall in the same section., Conclusion: The hemodynamic research of aortic arch based on CFD may actually simulate the characteristics of blood flow and wall stress so as to become a new reliable and convenient application tool in etiological diagnosis and surgical planning.

Objective: To establish a patient-specific hemodynamics model of thoracic aortic aneurysm (TAA) based on computational fluid dynamics technique and investigate its role in the study of growth and rupture mechanism of TAA., Methods: 3D realistic model of thoracic aortic aneurysm was reconstructed from DICOM format computed tomography angiography (CTA) images of a male patient. The geometry was reconstructed using medical image processing software Mimics. The blood flow in aorta was assumed to be laminar and incompressible and the blood Newtonian fluid. A time-dependent pulsatile boundary condition was deployed at inlet. Unsteady blood flow simulation was performed in real geometry of TAA with a finite volume method (FVM) code FLUENT. The hemodynamic parameters related with the growth and rupture of aneurysm were analyzed., Results: Analysis of the distributions of hemodynamic variables during the cardiac cycle such as wall shear stress, streamlines and velocity profiles in TAA were carried out. The numerical simulation results demonstrated that the blood velocity of proximal neck was considerably faster than that of aneurysm body. The outer wall of proximal aneurysm body was hit by blood jet entering aneurysm. Instant streamlines at peak systole showed that the entering blood stream hit the aneurysm wall and right-hand helical vortex was observed in aneurysm body. The distributions of high wall shear stress were observed in the proximal and distal aneurysm neck and the area where the entering blood stream first hit the wall. Large regions of lower wall shear stress occurred in aneurysm body., Conclusion: The growth and rupture mechanisms of TAA may be analyzed based on a constructed patient-specific model and hemodynamic simulation.

Objective: To observe and evaluate the pathologic changes and curative effects of irinotecan (CPT-11), 5-fluorouracil (5-FU) and combined short-term radiotherapy before low-set rectal cancer operation so as to provide a theoretic basis for formulating a new effective adjuvant therapeutic regimen., Methods: A total of 41 patients of low rectal cancer were treated with CPT-11, 5-FU therapy or CPT-11 plus 5-FU combined short-term radiotherapy from April 2002 to April 2009. They were divided into 2 groups according to different treatment schemes, including irinotecan group (n = 18) and irinotecan combined short-term radiotherapy group (n = 23). The pathologic changes before and after treatment were observed and the differences of two treatment approaches compared., Results: Tumor cells had different degrees of degeneration and necrosis under microscope in two groups. Compared with computed tomographic findings before therapy, tumor sizes of two groups were reduced by an average of 33.1% (13.5 mm vs 20.2 mm) and 34.4% (12.8 mm vs 19.5 mm) respectively. Two groups were graded according to the RCRG (rectal cancer regression grade) score: RCRG1: 7 cases vs 18 cases, RCRG2: 4 cases vs 3 cases and RCRG3: 7 cases vs 2 cases. According to the pathologic evaluation standard, 3-degree necrosis, cell interstitial fibrosis and intimal thickening in vessels were observed in two groups: 7 cases vs 17 cases, 6 cases vs 17 cases and 3 cases vs 14 cases respectively (all P < 0.05). Five patients achieved complete pathological remission in the irinotecan combined short-term radiotherapy group., Conclusion: Based on the pathological changes and mitigation results after treatment, CPT-11 and 5-FU may be used as neoadjuvant drugs for rectal cancer. If the above two drugs can be used in combination with short-term radiation, the curative effect will be better.

Objective: To evaluate the expressions of CD4+ CD25high CD127low/- regulatory T cells (Treg) in peripheral blood from patients with transitional cell carcinoma (TCC) in urinary system., Methods: The proportion of Treg population in CD4+ T cells from 93 patients with transitional cell carcinoma was evaluated. And flow cytometry was employed to analyze different clinicopathologic characteristics and detect the pre- and post-operative changes in 38 patients with benign urinary diseases and 37 healthy subjects., Results: The proportion of Treg population in CD4+ T cells in peripheral blood of patients with TCC significantly increased as compared with those with benign urinary diseases and healthy subjects. There was a strong correlation between the proportion of Treg and tumor recurrence, quantity, lymph node metastasis (P < 0. 01) as well as pathological stage; no correlation was found between the proportion of Treg and clinical TNM stage (P > 0. 05). The proportion of Treg was also different at pre- and post-operation (P < 0. 05)., Conclusion: CD4+ CD25high CD127low/- regulatory T cells in peripheral blood from patients with TCC significantly increased as compared with that in patients with benign urinary diseases and in healthy subjects. It may be responsible for immune suppression in TCC patients. Tumor resection could decrease the proportion of Treg in peripheral blood, but the long-term change in immune function requires further investigations.