Biosafety of the Novel Vancomycin-loaded Bone-like Hydroxyapatite/Poly-amino Acid Bony Scaffold / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>Recently, local sustained-release antibiotics systems have been developed because they can increase local foci of concentrated antibiotics without increasing the plasma concentration, and thereby effectively decrease any systemic toxicity and side effects. A vancomycin-loaded bone-like hydroxyapatite/poly-amino acid (V-BHA/PAA) bony scaffold was successfully fabricated with vancomycin-loaded poly lactic-co-glycolic acid microspheres and BHA/PAA, which was demonstrated to exhibit both porosity and perfect biodegradability. The aim of this study was to systematically evaluate the biosafety of this novel scaffold by conducting toxicity tests in vitro and in vivo.</p><p><b>METHODS</b>According to the ISO rules for medical implant biosafety, for in vitro tests, the scaffold was incubated with L929 fibroblasts or rabbit noncoagulant blood, with simultaneous creation of positive control and negative control groups. The growth condition of L929 cells and hemolytic ratio were respectively evaluated after various incubation periods. For in vivo tests, a chronic osteomyelitis model involving the right proximal tibia of New Zealand white rabbits was established. After bacterial identification, the drug-loaded scaffold, drug-unloaded BHA/PAA, and poly (methyl methacrylate) were implanted, and a blank control group was also set up. Subsequently, the in vivo blood drug concentrations were measured, and the kidney and liver functions were evaluated.</p><p><b>RESULTS</b>In the in vitro tests, the cytotoxicity grades of V-BHA/PAA and BHA/PAA-based on the relative growth rate were all below 1. The hemolysis ratios of V-BHA/PAA and BHA/PAA were 2.27% and 1.42%, respectively, both below 5%. In the in vivo tests, the blood concentration of vancomycin after implantation of V-BHA/PAA was measured at far below its toxic concentration (60 mg/L), and the function and histomorphology of the liver and kidney were all normal.</p><p><b>CONCLUSION</b>According to ISO standards, the V-BHA/PAA scaffold is considered to have sufficient safety for clinical utilization.</p>

Quantitative evaluation on the effectiveness of prevention and control measures against pandemic influenza A (H1N1) in Beijing, 2009 / 中华流行病学杂志

Objective To quantitatively evaluate the effectiveness of prevention and control measures against pandemic influenza A (H1N1) in Beijing, 2009 and to provide evidence for developing and adjusting strategies for prevention and control of the disease. Methods Considering the seasonality and the number of vaccination on pandemic influenza A (H1N1) , data regarding pandemic influenza A (H1N1) in Beijing were collected and analyzed. Based on the dynamics of infectious disease transmission, a quantitative model for evaluation of prevention and control measures was developed. Results Both latency and infectious periods of pandemic influenza A (H1N1) were estimated to be 1.82 days and 2.08 days, respectively. The effective reproduction numbers of the three periods were 1.13,1.65 and 0.96, respectively. Thanks to the implementation of a series of measures to prevent and control pandemic influenza A (H1N1), the cumulative number of laboratory-confirmed cases of pandemic influenza A (H1N1) was reduced, making it much smaller than what would have been under the natural situation. Specifically, the program on pandemic (H1N1) 2009 vaccination reduced the cumulative number of laboratory-confirmed cases by 24.08% and postponed the peak time. Conclusion Measures that had been taken during this period, had greatly contributed to the successful prevention and control of pandemic influenza A (H1N1). The 2009 Pandemic (H1N1)vaccination was confirmed to have contributed to the decrease of cumulative number of laboratoryconfirmed cases and postponed the peak arrival time.

The effects of tetrandrine on activity of collagenase derived from human hypertrophic scar / 中华整形外科杂志

<p><b>OBJECTIVE</b>To observe the effect of tetrandrine on activity of collagenase derived from human hypertrophic scar for the sake of clarifying the mechanism as tetrandrine acting on scar.</p><p><b>METHODS</b>The experimental concentration was controlled below that of cell proliferation inhibited, SDS-PAGE electrophoresis was adopted to separate collagenase from extracellular matrix, and then activated by trypsin analyzed the activity of collagenase with density scanning apparatus. At the same time quantity of extracellular collagen was measured using improved chloraseptine T oxidizing assay, moreover analyzed correlation between activity of collagenase and quantity of extracellular collagen.</p><p><b>RESULTS</b>In the concentration below the lever of inhibiting fibroblast proliferation, the total activity of collagenase could be significantly increased by tetrandrine with dosage-dependence associated with quantity of extracellular collagen reduced, which was much greater than that of triamcinolone.</p><p><b>CONCLUSION</b>Increasing activity of collagenase on degradation of collagen even in a lower concentration was one of the mechanisms of tetrandrine treating hypertrophic scar.</p>