Polylactic acid (PLA) and its copolymer are biodegradable polymer materials which are widely used in the medical field because of their excellent mechanical properties, chemical stability, good biocompatibility, and biodegradability. In this paper, research advances in the study on polylactic acid and its application in vascular stent are discussed.

Objective To investigate the effects of basic fibroblast growth factor (bFGF) on global cerebral ischemia/reperfusion (I/R) injury.Methods Twenty-four rabbits of both sexes aged 6 months weighing 2.2-3.0 kg were randomized into 3 groups ( n = 8 each) : group I sham operation; group Ⅱ I/R and group Ⅲ I/R + bFGF. The animals were anesthetized with diazepam, haloperidol and fentanyl. The right femoral artery was cannulated for BP monitoring and blood-letting. The animals were tracheotomized and mechanically ventilated (VT = 8 ml ?kg -1 , RR = 40 bpm, I: E = 1:2). PET CO2 was maintained at 40 mm Hg. Global cerebral I/R was induced by "occlusion of four vessels + hypotension" . Bilateral common carotid arteries and vertebral arteries were occluded for 30 min combined with hypotension, which was produced by blood-letting and maintained at 50%-60% of the baseline level. The four vessels were then released for reperfusion and BP was returned to baseline level by retrieval of the removed blood. In sham operation group ( Ⅰ ) the four blood vessels were exposed but not occluded. In group Ⅲ a loading dose of 30 ?g?kg-1 bFGF was given Ⅳ at the end of 30 min ischemia followed by bFGF infusion at 10 ?g? kg-1? h-1 for 6 h. In I/R group ( Ⅱ ) normal saline was given IV instead of bFGF. Blood samples were taken before I/R (T0 , baseline) and at 0, 0.5, 1, 3, 6 h (T1-5) of reperfusion for determination of serum neuron specific enolase (NSE) and S-100B concentrations. At the end of the experiment the animals were killed and brains removed for determination of brain water content and microscopic examination. Results Serum NSE and S-100B concentrations in group Ⅱ and Ⅲ were significantly increased at T4 5 as compared to the baseline (T0) and were significantly higher at T4 5 than those in sham operation group ( Ⅰ ) . Serum NSE and S-100B concentrations were significantly lower in group Ⅲ (I/R + bFGF) than in groupⅡ (I/R). Serum NSE and S-100B were positively correlated ( r = 0.736, P

Objective To determine the appropriate size of the tube for the thoracic drainage in good efficiency by the experimental study in the influence of the tube size on the flow rate of the fluid with different properties.Methods Three groups were divided according to the different components in the fluid:group A,whole blood with 30％ hematocrit; group B,2.5％ albumin solution; and group C,0.9％ normal saline.The total volume of the fluid was 1000 mL in each group in the experiment.Different sorts of fluids were drained with the chest tubes with different diameters (6F,8F,10F,12F,14F,16F,18F,20F,22F,24F,26F,28F,30F,32F,34F,36F of French F) separately,and the flow rate was calculated.ANOVA was used for the comparison of the differences in flow rate among the groups with given fluid property.Twofactor analysis of variance was used for the analysis of flow rates of fluid with different fluid properties.Curve fitting was performed according to the Poiseuille formula.Results The flow rate was positively correlated with the size of the chest drainage tube.The difference in flow rate among the tubes with difference in size was statistically significant (P ＜ 0.05) but there was no noticeable difference in flow rate between 6F and 8F (P =0.513).The flow rate of the 6F and 8F tubes was higher than that of the control (3.33 mL/min) but there was no significant difference between them (P ＞ 0.05).The flow rate of the tubes in 10F and above was obviously higher than that of control (P ＜ 0.05).The curve was estimated that group A was Q =0.002 9x4,R2 =0.991; group B Q=0.003 2x4,R2 =0.981; group C Q =0.003 4x4,R2 =0.975.When the flow rate was fixed at 3.33 mL/min,the estimated curve in group A was X ≈ 5.82F.Conclusions Our experiment indicated that the chest tube with small diameters (6F-14F) could meet the demand of high efficient drainage in the patients with hemothorax or pleural effusion.

Objective To identify the potential risk factors affecting mortality rate of ALl in severe trauma population. Method It was a retrospective cohort study treating trauma as a single cause for emergency depart-ment (ED)) and emergency intensive care unit (EICU) admissions. Eighteen potential risk factors affecting the mortality of ALI were examined by univariate and multivariate logistic analyses in these severe trauma patients. Re-sults There were 343 severe trauma patients with post-traumatic ALI admitted to ED and EICU the Second Affili-ated Hospital Medical College,Zhejiang University,during the study period. The five risk factors that affected the mortality with unadjusted odd ratios (ORs) and 95% confidence intervals (CIs) were (1) APACHE Ⅱ score, (2)duration of trauma, (3) age, (4) aspiration of gastric contents, and (5) DIC. Specific risk factors also affected different patients subpepulations at different degrees. Conclusions Factors of APACHE Ⅱ score and aspiration of gastric contents that can predict the mortality of ALl may exist in the early stage of trauma. Duration of trauma and DIC that greatly affect the short- and long-term development of ALI deserve special attention. Elderly patients (aged beyond 65 years) are the independent risk factor for the secondary sepsis and deterioration of pulmonary function. Patients with these risk factors need aggressive supportive care as early as possible in order to prevent fur-ther aggravation.

OBJECTIVETo review the research methods of mass casualty incident (MCI) systematically and introduce the concept and characteristics of complexity science and artificial system, computational experiments and parallel execution (ACP) method.

DATA SOURCESWe searched PubMed, Web of Knowledge, China Wanfang and China Biology Medicine (CBM) databases for relevant studies. Searches were performed without year or language restrictions and used the combinations of the following key words: "mass casualty incident", "MCI", "research method", "complexity science", "ACP", "approach", "science", "model", "system" and "response".

STUDY SELECTIONArticles were searched using the above keywords and only those involving the research methods of mass casualty incident (MCI) were enrolled.

RESULTSResearch methods of MCI have increased markedly over the past few decades. For now, dominating research methods of MCI are theory-based approach, empirical approach, evidence-based science, mathematical modeling and computer simulation, simulation experiment, experimental methods, scenario approach and complexity science.

CONCLUSIONSThis article provides an overview of the development of research methodology for MCI. The progresses of routine research approaches and complexity science are briefly presented in this paper. Furthermore, the authors conclude that the reductionism underlying the exact science is not suitable for MCI complex systems. And the only feasible alternative is complexity science. Finally, this summary is followed by a review that ACP method combining artificial systems, computational experiments and parallel execution provides a new idea to address researches for complex MCI.