Objective To introduce a finger leaf design that is applied to dual layer MLCs.Methods An optimization model was firstly constructed to describe the problem of determining leaf end shapes,and the corresponding problems were then solved by the simplex search method or the simulated annealing technique.Optimal parameters for arc shapes of leaf end projections were obtained,and a comparison was done between optimized MLCs and conventional MLCs in terms of field conformity.The optimization process was based on 634 target fields selected from the patient data base of a treatment planning system.Areas of these fields ranged from 20.0 to 602.7 cm with a mean and its standard deviation of (125.7 ±0.0) cm~2.Results The optimized leaf end shapes projected to the isocenter plane were semicircles.With the finger leaf design,the total area of discrepancy regions between MLC fields and target fields was reduced by 32.3% .Conclusions The finger leaf design improves the conformity of the MLC shaped fields to the desired target fields.

Tissue engineering has always been a hot spot in the life science area over the past few years. However, there are some problems, such as the multiplication of seeding cells, the preparation of tissue engineering scaffolds, and the controlled release of drugs from scaffolds and so on. Recently microspheres have been widely used to solve these problems. For example, microspheres are used as microcarriers to culture seeding cells. In addition, microsphers can be either used to prepare engineering scaffolds or directly used as scaffolds. Microspheres can be used to load drugs and control the drug release as well. In this paper the application of microspheres in tissue engineering is reviewed and the up-to-date methods are introduced, including ways of improving performances of microcarriers, preparing scaffolds with microspheres and adding drug-loaded microspheres into scaffolds.

The response of normal islet β cells to insulin resistance is compensatory insulin hypersecretion in order to maintain normoglycemia. The mechanisms involved in the compensation process including the expansion of β cell mass and enhanced β cell performance via various molecular cascades, signaling pathway sand their interactions have been extensively investigated in recent years.

The study on medical education directly affects the quality of education and cultivation of medical professionals as well as the level of running school.It is very important for the medical colleges to take some measures to solve these problems existing in medical teaching reform and research,such as renewing teachers' ideas,enhancing the standardization of management,increasing the enthusiasm of the teachers etc.

Objective To compare the relative accuracy of single-plane and biplane area-length methods for determining right ventricular (RV) volume and ejection fraction (RVEF) both in vitro and in vivo studies. Methods The in vitro study consisted of 15 human right ventricular casts and the in vivo study consisted of 45 patients. RV volume by single-plane area-length method was determined by the product of RV area from apical four-chamber view and the distance from RV apex to tricuspid annulus. RV volume by biplane area-length method was defined as 2/3?(the product of RV area from apical four-chamber view and the distance from pulmonary valve to tricuspid valve). The actual volume of RV casts was determined by water displacement method. RV angiography was used to determine RV volumes and RVEF in the in vivo study. Results RV volumes calculated from both single-plane and biplane methods correlated closely with RV cast volumes in the in vitro study (r= 0.87- and 0.91-, respectively; both P 0.05-), but RV volume determined by single-plane method significantly overestimated angiographic volume (P

AIM: To investigate the possibility of 3T3 fibroblast growth on blood fibrin clot in culture medium with recombinant human basic fibroblast growth factor (rhbFGF). METHOD: Growth of the cells on blood fibrin clot was studied by phase-contrast, scanning and transmission electron microscopy and by Giemsa stain and MTT assay. RESULTS: The optimal concentration of rhbFGF for proliferation and survival of the cells was 100 ng/mL. The cells also grew on blood fibrin clot scaffold in the low-serum medium containing 100 ng/mL rhbFGF, and a greater number of the cells survived after 48 hours incubation compared to that after 24 hours. The elongated filopodia appeared to bridge the gaps among the fibroblasts after 24 hours incubation. Further incubation to 72 hours, a greater number of platycytes were found to be joined together by lamellopodia. CONCLUSION: 3T3 fibroblasts could grow and survive on blood fibrin clot in the low-serum medium containing rhbFGF, and a combination of blood fibrin clot and rhbFGF may have over proportional effects on wound healing.

Objective To study the effects of uhrashortwave and low frequency pulsed electromagnetic fields on the expression of vascular endothelial growth factor(VEGF) in fracture healing. Methods Fifty-six New Zeal-and rabbits with artificial fractures were randomly divided into 4 groups:a control group,an ultrashortwave group,a low frequency pulsed electromagnetic field group and an ultrashortwave combined with low frequency pulsed electro-magnetic field group(combined group),with 14 in each group.Radiographic evaluation of callus formation and frac-ture healing,pathohistological examination and detection of VEGF expression through immunohistochemical staining were performed at the 1 st,2nd,4th and 6th week after the operation. Results Radiographic examination showed that there was significantly greater callus formation in the combined group than in the other groups throughout the healing process. Pathohistological examination also revealed significantly more cartilage islets and callus formation in the combined group.At the 1 st,2nd and 4th week after the operation,VEGF positive indexes in the combined group were significantly higher than in the other groups. Conclusion Uhrashortwave combined with low frequency pulsed electromagnetic field exposure can up-regulate the expression of VEGF and thus can accelerate fracture healing.

In this paper, we investigated five model counties for their application of medical technologies to explore the mechanism for sustainable development of appropriate medical technologies in rural areas of Ningxia, The investigation involved the governmental role at all levels in the choice of appropriate technologies, the funding system, the stimulation system and the evaluation system.

OBJECTIVE:To discuss the accuracy of detecting tacrolimus(FK506) concentration in whole blood by ELISA and its application in organ transplantation.METHODS:The ELISA was used to detect FK506 valley point concentrations in 5 liver transplanted recipients at different postoperative periods .Based on the results combined with clinical findings, the dosages were adjusted.The accuracy of the method and guidance action in FK506 clinical application were described.RESULTS: In 131 detections of 350 samples, the results of quality control samples were all in the control range .The detecting RSDs of high and low concentration quality control samples were 9.09% and 11.90%, respectively.The control range of FK506 concentrations in whole blood were similar to that reported in literature .CONCLUSION :ELISA is a sensitive and specific method for routine FK506 concentration monitoring in whole blood,which is suitable for application in hospital.

Objective: To prepare an adenovirus, Ad-CD, expressing bacterial cytosine deaminase(CD),and use it for tumor suicide gene therapy. Methods: We constructed a recomb ined adenoviral vector carrying CD or LacZ. 293 packaging cell was trans fected by the newly-constructed plasmid and generated the infectious virus. The n the adenovirus was used to infect C26 cell in vitro. Results: The growth of Ad-CD-infected cell was obviously surpressed after admini stration of 5-FC. Conclusion: CD gene carried by adenoviral vec tor is effective for tumor cell suicide gene therapy in vitro.