[Abstract ] Objective At present, the majority of injectable tissue engineering bones or carrier stents are gel , whose surface area , intensity, and hardness cannot satisfy the requirements of the repair of complex and varied bone and cartilage defects .This paper evaluated the new injectable microspherical porous chitosan/biological properties of the hydroxyapatite ceramic scaffold . Methods Injectable porous chitosan /hydroxyapatite composite microspheres with mass fractions of 30%, 50%, and 70% were prepared respectively . The hydroxyapatite ceramic ball was obtained by sintering with liquid nitrogen freezing ( liquid nitrogen group ) or without liquid nitrogen pro-cessing ( non-liquid nitrogen group ) as a new carrier of bone tissue engineering scaffold material .The microstructure of the scaffold was observed and the porosity measured under the scanning electron microscope .The mechanical properties were determined through biome-chanical experiments.Human umbilical vein endothelial cells (HUVECs) were grown in the porous chitosan/hydroxyapatite ceramic scaf-fold followed by observation of the growth of the cells and validation of the biological fusion of the scaffold . Results No difference was observed with the naked eye in the ceramic scaffold of different mass fractions in the liquid nitrogen and non -liquid nitrogen groups . Scanning electron microscopy exhibited spherical shape , uniform size, and regular morphology of the ceramic scaffolds in both groups .A large number of irregular pores were seen in the surface of the microspherical ceramic scaffolds treated with liquid nitrogen but not in the surface of those not treated .With increased mass percentage of chitosan/hydroxyapatite , the internal pores were reduced and the interior structure compacted.In the liquid nitrogen group, the scaffold of 50%mass fraction had a significantly larger diameter ([0.48 ±0.11] mm), higher compression intensity ([1.75 ±0.14] MPa), and lower porosity ([79 ±2]%) than that of 30%mass fraction ([0.40 ± 0.08] mm, [1.21 ±0.12] MPa, and [87 ±1]%) (all P<0.05).Electron microscope scanning revealed well -grown HUVECs with multiple synapses in the porous tricalcium phosphate scaffold. C onclusion The porous chitosan /hydroxyapatite ceramic scaffold of 50%mass fraction treated with liquid nitrogen , with its strong mechanical intensity and high biological fusibility , can be used as a new carrier of bone tissue engineering scaffolds .

Objective To observe the effect and the skin flap necrosis situation of low concentration methylene blue dye in sentinel lymph node biopsy of breast cancer compared with normal concentration methylene blue dye.Methods One hundred and thirty-eight cases patients with early breast cancer who were treat by sentinel lymph node biopsy surgery in Breast surgery Department of Sichuan ProvincialTumor Hospital from June 2016 to February were selected,and randomly divided into low concentration methylene blue dye group (n =69) and common concentration methylene blue dye group (n =69).Observed and recorded the sentinel lymph node detection and skin flap necrosis of relevance ratio(1％ and 0.1％ concentration methylene blue dye) concentration methylene blue dye in both two groups.Results There were no significant differences in terms of number of sentinel lymph node detection,the detection rate and false negative rate in two groups,while the rate of cutaneous necrosis in low concentration methylene blue dye group was lower (5.8％ vs.0％,P =0.025).Conclusion The effect of low concentration methylene blue dye in sentinel lymph node biopsy of breast cancer is the same as that of common concentration while the low concentration group with fewer side effects.