Tissue-engineered calcium phosphate cement in rabbit femoral condylar bone defects

Background Calcium phosphate cement （CPC） is a favorable bone-graft substitute, with excellent biocompatibility and osteoconductivity. However, its reduced osteoinductive ability may limit the utility of CPC. To increase its osteoinductive potential, this study aimed to prepare tissue-engineered CPC and evaluate its use in the repair of bone defects. The fate of transplanted seed cells in vivo was observed at the same time. Methods Tissue-engineered CPC was prepared by seeding CPC with encapsulated bone mesenchymal stem cells （BMSCs） expressing recombinant human bone morphogenetic protein-2 （rhBMP-2） and green fluorescent protein （GFP）. Tissue-engineered CPC and pure CPC were implanted into rabbit femoral condyle bone defects respectively. Twelve weeks later, radiographs, morphological observations, histomorphometrical evaluations, and in vivo tracing were performed. Results The radiographs revealed better absorption and faster new bone formation for tissue-engineered CPC than pure CPC. Morphological and histomorphometrical evaluations indicated that tissue-engineered CPC separated into numerous small blocks, with active absorption and reconstruction noted, whereas the residual CPC area was larger in the group treated with pure CPC. In the tissue-engineered CPC group, in vivo tracing revealed numerous cells expressing both GFP and rhBMP-2 that were distributed in the medullar cavity and on the surface of bony trabeculae. Conclusion Tissue-engineered CPC can effectively repair bone defects, with allogenic seeded cells able to grow and differentiate in vivo after transplantation.

Software defect prevention based on human error theories

Software defect prevention is an important way to reduce the defect introduction rate.As the primary cause of software defects,human error can be the key to understanding and preventing software defects.This paper proposes a defect prevention approach based on human error mechanisms：DPe HE.The approach includes both knowledge and regulation training in human error prevention.Knowledge training provides programmers with explicit knowledge on why programmers commit errors,what kinds of errors tend to be committed under different circumstances,and how these errors can be prevented.Regulation training further helps programmers to promote the awareness and ability to prevent human errors through practice.The practice is facilitated by a problem solving checklist and a root cause identification checklist.This paper provides a systematic framework that integrates knowledge across disciplines,e.g.,cognitive science,software psychology and software engineering to defend against human errors in software development.Furthermore,we applied this approach in an international company at CMM Level 5 and a software development institution at CMM Level 1 in the Chinese Aviation Industry.The application cases show that the approach is feasible and effective in promoting developers＇ ability to prevent software defects,independent of process maturity levels.

A diagnostic kit to screen individuals with glucose-6-phosphate dehydrogenase defect and its application on anti-malaria spot in the countryside

Objective To prepare a kit for screening individuals with glucose 6 phosphate dehydrogenase (G6PD) defect. The kit is easy to use and to get the fast as well as reliable results. Especially it is suitable for the anti malaria spots usually located in the remote countryside where no electricity is available. Methods The double filter paper method and other 2 techniques, the quantitative method and the single filter paper method, were used to determine G6PD activity in 70 samples of human erythrocytes. It was found that the results of the double filter paper method and those of the single filter paper method in the first 8 hours after the drying of the blood soaked filter paper were consistent with those of the quantitative method. When a piece of blood soaked paper is left under room temperature more than 24 hours, G6PD in the erythrocytes deteriorated spontaneously and consequently the number of positive cases increased along with the elapse of time.Results Satisfactory results were achieved when the kit was used to screen cases of G6PD defect from 151 farmers who were receiving anti mararia therapy. The kit was made according to a technique named “double filter paper” method.Conclusions These findings suggest that the double filter paper method can reveal the level of G6PD activity and the results are rapidly obtained when the method is used on the anti malaria spot.