Objective To examine the segmental bone defects healing by ? TCP/rhBMP 2 composites with different degradation rate and discuss the relationship between osteogenesis and degradation of ? TCP in vivo. Methods Three kinds of ? tricalcium phosphate(? TCP) with different degradation rate (? TCP1-3) were prepared by means of different techniques. ? TCP/rhBMP 2 composites with different degradation rate(? TCP1/rhBMP 2 and ? TCP2/rhBMP 2)were obtained by combining ? TCP1, ? TCP2 with recombinant human bone morphogenetic protein 2(rhBMP 2), respectively. ? TCP1/rhBMP 2, ? TCP2/rhBMP 2, ? TCP1, ? TCP2 and ? TCP3 were used to repair 15 mm radial segmental defects in 81 Chinese rabbits. When the samples were harvested in 4, 8, 16 and 24 weeks after surgery, a series of examination were carried out, including the roentgenographical, histomorphological, biomechanical and computerized graphical analysis, energy dispersion analysis X ray (EDAX), and measurements of inorganic contents. Results Roentgenographically and histologically, all of the defects that had been treated with implants exhibited new bone formation, increasing with time. The quantity and rate of new bone formation in ? TCP1/rhBMP 2 group and ? TCP2/rhBMP 2 group were higher than those in group of ? TCP alone. The ability of new bone formation in ? TCP1/rhBMP 2 group was strongest. At 24 weeks the defects in ? TCP1/rhBMP 2 group were bridged with the appearance of marrow cavities, the inorganic contents and ratio of calcium to phosphate and biomechanical property in implants approached to those of normal bone. Although degradation occurred to some extent in ? TCP alone the degradation were faster in ? TCP/rhBMP 2 composites. At 24 weeks the degradation rate in ? TCP1/rhBMP 2 group and ? TCP2/rhBMP 2 group were 97.4%and 73.4%, respectively. The defects in blank controls were repaired only by fibrous tissue at 24 weeks. Conclusion ? TCP/rhBMP 2 composites with different degradation rate could repair segmental bone defects, and osteogenesis could accelerate the degradation of ? TCP in vivo.

The methods, present research situation, existing problems, and application foreground of multidimensional reconstruction of ultras onic heart images are discussed in the present paper. According to the procedure of multidimensional reconstruction of ultrasonic heart images, the discussions are presented in respect toimage acquisition, processing, and display. Based on the present situation and existing problems, the future development and applica tion foreground are proposed.

Several kinds of filters for medical ultrasonic images, suchas multidimensional filter, adaptive weighted filter (for example, adaptive weighted median filter), adaptive window selecting filter (for example , homogeneous region growing mean filter and adaptive speckle suppression filter ) and two-step filter, are introduced. The existing problems and the progress trend are also discussed. Some application instances for medical ultrasonic images of the filters discussed and the performance of the filters presented are based on the present authors' practice.

Contour detection is one of the most difficult problems in the multi-dimensional reconstruction of echocardiographic images. A method based on active contour model is presented in the present paper to solve this problem. First, according to the characteristic of the ultrasonic medical images, an adaptive weighted median filter is used to suppress speckle noise and an adaptive threshold value is selected to get binary image. Then, mathematical morphological treatment is utilized to get the initial contour. At last, active contour model is employed to revise the initial contour and get the accurate final contour. Experiments with real and interpolated ultrasonic images are presented. The results show the effectiveness of this method. This method has practical use in the multi-dimensional reconstruction of ultrasonic medical images.

Objective To improve the precision of the traditional segmentation of echocardiogram, by suppressing the influence from inherent speckle noises in medical ultrasonic images. Method An automatic segmentation method based on reconstructed morphology was proposed in this paper. First, the opening and closing operations by reconstruction were imposed to the ultrasonic image. Second, the top-hat operation was used to extract the bright and/or dark features and to find out the boundaries corresponding to these features, whereby implemented the automatic segmentation. Result The segmented echocardiogram had less artificial boundaries resulted from speckle noise, and could accurately be extracted the artery and ventricle. Conclusion The presented method can detect both dark and bright objects accurately, and the boundary has a fine continuity. In addition, the algorithm is also applicable to the extraction of sole bright/dark features, accordingly to reduce the complexity and time needed and to improve the accuracy.

During the preparation of functional gradient materials (FGM) with plasma immersion ion implantation-ion beam enhanced deposition (PIII-IBED), the combination strength between the coating and the substrate would be greatly affected by the implantation dose and the distribution of implanted ions in substrate. According to the requirements of FGM, an idea of multi grades energy implantation had been suggested, with which the Gauss peak could be moved toward the surface, and the concentration of implanted ions could be maximized at the surface. In this study, the distribution of carbon ions implanted into titanic alloy substrate have been simulated theoretically, and the tentative idea have been confirmed experimentally.
Alloys ; Carbon ; Coated Materials, Biocompatible ; chemical synthesis ; Computer Simulation ; Heart Valve Prosthesis ; Titanium

Studies on bioactive glass and glass-ceramic are important research high-lights in the field of biomedical materials. Due to their bioactivity, these materials can form a tight chemical bond with the living bone, when implanted. As a preeminent kind of these materials, A-W(Apatite/Wollastonite) bioactive glass ceramic has not only the excellent bioactivity and biocompatibility, but also the eminent mechanical properties, so it has been largely applied and developed in clinical practice. The development, preparation, properties, applications and the mechanism of its bond with bone are introduced in this paper. We will also put forward the prospect of the research and development of A-W bioactive glass ceramic.
Apatites ; chemistry ; Bone Substitutes ; chemistry ; Calcium Compounds ; chemistry ; Ceramics ; chemistry ; Mechanics ; Research ; Silicates ; chemistry ; Surface Properties

A promising alternative to supply bone substitutes is to develop living tissue substitutes based on biodegradable materials, which is called bone tissue engineering. One of the research high-lights of bone tissue engineering is to design and manufacture scaffolds for cell attaching, migrating, and proliferating. A process which consists of a solvent casting stage, a compression molding stage and a leaching stage has been used to fabricate macroporous composites of poly(l-lactic acid)(PLLA) and β-tricalcium phosphate (β-TCP). The effects of the weight fraction of porogen-NaCl, of the weight ratio of PLLA to β-TCP and of the diameters of β-TCP on the porosities, the average pore diameters and the compressive yield strength and compressive modulus have been studied. The results showed that the porosities and the average pore diameters increased and the compressive yield strength and modulus decreased when the weight fraction went from 50% to 90%. The compressive yield strength and compressive modulus could be improved by changing the weight ratio of PLLA to β-TCP and the diameters of β-TCP in low-porosity composites (lower than 70%). But high-porosity composites (90%) were not reinforced by changing the weight ratio.

Diamond-like carbon(DLC) was prepared by means of plasma source ion implantation-ion beam enhanced deposition. Through the heat treatment upon DLC in air and in depressed Ar gas, the DLC rich in graphite, DLC rich in diamond, and other kinds of DLC used in the study were obtained respectively. For the three kinds of DLC, the components of carbonaceous phase were analysed by X-ray photoelectron spectroscopy (XPS), the adsorptive amounts of human serum albumin (HSA), human serum fibrinogen (HFG) and human serum immunoglobin (IgG) on their surfaces in the condition of constant temperature were determined by radio isotope 125I labelling method. Results showed the graphite phase and diamond phase in DLC increased by two times or so respectively after the aforementioned different heat treatment. In pace with the increase of these foreign phases, the adsorptive amounts of HFG and IgG on DLC greatly increase but the adsorptive amounts of HSA on DLC decrease; furthermore, there is a change from non-selective adsorption of three human serum proteins into selective adsorptions of HFG and IgG prior to HSA. These results indicate that the foreign phases in DLC such as graphite, diamond, C-H phase and C-O phase have a great effect on protein adsorption on DLC and hence a negative effect on the hemocompatibility of DLC. The mechanisms for the increase of graphite phase and diamond phase in the process of heat treatment were also discussed in this paper.
Adsorption ; Biocompatible Materials ; chemistry ; Carbon ; chemistry ; Diamond ; chemistry ; Fibrinogen ; metabolism ; Humans ; Immunoglobulin G ; metabolism ; Proteins ; metabolism ; Serum Albumin ; metabolism ; Surface Properties

The design and development of multi-dimensional ultrasonic reconstruction and visualization system (MURVS) have been described in the present paper. This system is basically composed of four modules: the data input/output module, image segmentation and arrangement module, multi-dimensional reconstruction module, and the dynamic visualization module. At first, some algorithms used in the system are introduced by the authors, including the AVI segmentation algorithm, three-dimensional interpolation algorithm, and volume rendering algorithms. Then the key questions of techniques to be discussed are: how to design the main modules, how to solve the dynamic visualization problem, and how to implement the system. The experiments indicate that MURVS is able to reconstruct all three-dimensional data fields in one cardiac cycle of a patient within 4 seconds, and dynamically display the motion of the heart. It allows the medical professionals to select different parameters when observing the reconstructed results. This is very helpful for medical professionals to reach more accurate diagnoses of their patients' diseases.
Adult ; Algorithms ; Echocardiography, Three-Dimensional ; methods ; Female ; Humans ; Image Processing, Computer-Assisted ; methods ; Mitral Valve Stenosis ; diagnostic imaging