Tissue engineering is a kind of cross subject,which develops on the basis of cell biology,molecular biology,bio-material science and clinical medicine.The aim of tissue engineering is to restore and improve the function of scathing tissue using bio-substituent.The basis of tissue engineering is to study and develop the frame materials of bio-substituent.Besides the physical and chemical properties satisfying the growth and reproduction of the seed cell,the materials should hold the following properties,including tissue compatibility,bio-degradability,degradable modulability,nontoxicity,easy to mold.The materials studied extensively are PLA and PGA.The polylacticacids frame materials have been used to be the frame materials of bone,cartilage gristle,blood vessel,nerve and skin.The preparation of polylacticacids and its improvement are reviewed in this article.The application development to tissue engineering is also presented.

Objective To study the reason and the preventive measures that adverse effects of extracorporeal shockwave lithotripsy (ESWL) for renal stones during treatment.Methods From April 2015 to January 2016,165 patients who underwent ESWL treatment for renal stones were enrolled this retrospective study.All patients were in supine position.Direction of shockwave was by the path of preabdomen.The adverse effects during treatment were observed.The related factors were analyzed by Logistic regression analysis.Results There were 70 cases(42.4％) with pain,10 cases(6.1％) with cold sweat,8 cases (4.8％) with accelerated heart rate,5 cases (3.0％)with descent of heart rate,2 cases (1.2％) with nausea and vomiting.In the univariate Logistic regression analysis,four variables (BMI,history of ESWL treatment,stone location and energy) were found showing statistical significance.Multivariate Logistic regression analysis showed that the final significant related factors were BMI ＜ 24.0 kg/m2 (OR =4.155,CI 1.373-12.571),history of ESWL treatment (OR =0.163,CI 0.058-0.454),stone in pelvis(OR =123.051,CI 17.638-858.439),stone in middle calyceal (OR =169.171,CI 29.677-964.343),energy 86.3-94.7J (OR =0.094,CI 0.025-0.362).Conclusions Pain was the most common adverse effect during the treatment of ESWL.Stone location (pelvis and middle calyceal) was an independent risk factor,BMI ＜ 24.0 kg/m2 was one of the related risk factors.Both energy 86.3-94.7J and history of ESWL treatment were preventive factors.