Antimicrobial Activity of SCH 27899, Oligosaccharide Member of the Everninomycin Class with a Wide Gram-Positive Spectrum

The in vitro antimicrobial activity of SCH 27899 (everninomycin), a novel oligosaccharide compound of the everninomycin class, was compared with vancomycin, chloramphenicol, clinafloxacin, teicoplanin and doxycycline against 428 clinical strains of bacteria. Everninomycin base exhibited the greatest antimicrobial activity compared to other formulations against all strains tested (MIC₉₀: 0.25 μ/ml) followed by clinafloxacin and teicoplanin (MIC₉₀: 0.5 μg/ml), vancomycin (MIC₉₀: 2 μg/ml), and doxycycline (MIC₉₀: 16 μg/ml). Everninomycin demonstrated the best activity against Streptococcus spp. (serogroups A, B, C, F, G) and Streptococcus pneumoniae , and lower activity against coagulase-negative staphylococci (MIC₉₀: 0.5 μg/ml). All enterococci had an everninomycin MIC of 0.5 μg/ml or less. Everninomycin had no measurable antimicrobial activity against gram-negative aerobic organisms except Flavo-bacterium meningosepticum (MIC₅₀: 2 μg/ml). Some everninomycin activity was observed against Clostridium spp., Peptostreptococcus spp., and the Prevotella bivius-disiens group. Everninomycin showed excellent activity (MIC₉₀: 0.25 μg/ml) against the fluoroquinolone-resistant strains and all gram-positive strains resistant to vancomycin (MICs 4 μg/ml). The MBC/MIC ratios and killing curve data suggest that everninomycin is not uniformly or rapidly bactericidal. These in vitro data indicate that everninomycin could be useful against emerging gram-positive strains resistant to other contemporary antimicrobials.     

几丁糖/海藻酸敷料止血性能的实验研究

目的研究一种新型敷料：几丁糖／海藻酸敷料（本项目组自行研制，已申请国家专利）的止血性能。方法取新西兰兔4只，在背部两侧对称性剪5个直径1cm的圆型创口，分别与创面大小相当的几丁糖／海藻酸敷料和明胶海绵止血，观察与创面的粘附情况，记录出血时间：止血停止后，将几丁糖／海藻酸敷料和明胶海绵放入预先配制好的氰化高铁血红蛋白检测试剂中仔细清洗，用分光光度计在540nm波长处光度比色，测出的Hb光度吸收值表示出血量。结果几丁糖／海藻酸敷料与创面粘附较好，几丁糖／海藻酸敷料、明胶海绵组的出血时间分别为87.7±19.1妙、170.7±22.6妙，Hb光度吸收值分别为1.131±0.44、1.733±0.733，经统计学分析，两组数据都有显著性差异（P〈0.01），几丁糖／海藻酸敷料组明显优于明胶海绵组。结论几丁糖／海藻酸敷料具有较好的止血性能。     

Development and validation of a reverse-phase liquid chromatographic method for the assay of lidocaine hydrochloride in alginate-Gantrez microspheres

A simple, fast and reliable reverse-phase high-performance liquid chromatographic (HPLC) method was developed for the assay of lidocaine hydrochloride (LH) in Gantrez-alginate microspheres. Separation was achieved in a LiChrospher C18 column, using a mobile phase consisting of acetonitrile:ammonium acetate (0.0257 M) adjusted to pH 4.85 with acetic acid, in the ratio 70:30 (v/v) and a flow rate of 0.6 mL/min. The detection was made with a diode array detector measuring at the maximum for the compound. The validation study demonstrated that the method was precise, accurate and linear over the concentration range of analysis with a limit of detection of 0.001 mg/mL. The limit of quantification was 0.002 mg/mL. Linear regression analysis in the range of 0.8-2.4 mg/mL gave correlation coefficients higher than 0.995. The method developed was applied to the analysis of lidocaine in microsphere samples in order to evaluate in next papers, the encapsulation efficiency of different formulations.     

Bone-derived MSCs encapsulated in alginate hydrogel prevent collagen-induced arthritis in mice through the activation of adenosine A2A/2B receptors in tolerogenic dendritic cells

Tolerogenic dendritic cells (tolDCs) facilitate the suppression of autoimmune responses by differentiating regulatory T cells (Treg). The dysfunction of immunotolerance results in the development of autoimmune diseases, such as rheumatoid arthritis (RA). As multipotent progenitor cells, mesenchymal stem cells (MSCs), can regulate dendritic cells (DCs) to restore their immunosuppressive function and prevent disease development. However, the underlying mechanisms of MSCs in regulating DCs still need to be better defined. Simultaneously, the delivery system for MSCs also influences their function. Herein, MSCs are encapsulated in alginate hydrogel to improve cell survival and retention in situ, maximizing efficacy in vivo. The three-dimensional co-culture of encapsulated MSCs with DCs demonstrates that MSCs can inhibit the maturation of DCs and the secretion of pro-inflammatory cytokines. In the collagen-induced arthritis (CIA) mice model, alginate hydrogel encapsulated MSCs induce a significantly higher expression of CD39⁺CD73⁺ on MSCs. These enzymes hydrolyze ATP to adenosine and activate A_2A/2B receptors on immature DCs, further promoting the phenotypic transformation of DCs to tolDCs and regulating naïve T cells to Tregs. Therefore, encapsulated MSCs obviously alleviate the inflammatory response and prevent CIA progression. This finding clarifies the mechanism of MSCs-DCs crosstalk in eliciting the immunosuppression effect and provides insights into hydrogel-promoted stem cell therapy for autoimmune diseases.     

A dry powder formulation from silk fibroin microspheres as a topical auto-gelling device

With the aim of establishing the formulation of a new hydrophilic auto-gelling medical device for biomedical applications, fibroin-based microspheres were prepared. The proposed microspheres were produced by a cost-effective and industrially scalable technique, such as the spray-drying. Spray-dried silk fibroin microspheres were obtained and the effects of different hydrophilic polymer on the process yield, microsphere morphology and conformation transition of fibroin were evaluated. The final auto-gelling formulations were obtained by adding calcium gluconate (as a calcium source for alginate crosslinking) to the prepared microspheres and tested by an in vitro gelling test. This study showed that the combination of fibroin with sodium alginate and poloxamer produced the most promising auto-gelling formulation for specific biomedical applications, such as the treatment of pressure ulcers.     

Synergistic effect of microencapsulation and immunoalteration on islet allograft survival in bioartificial pancreas

Recently, we reported successful transplantation (Tx) of microencapsulated (mc) islets. However, graft failure observed in several cases was associated with an increased foreign body reaction compared to long-term functioning grafts. This study was performed to investigate the impact of an immunoalterating islet pretreatment (12–14 days culture at 22°C) on graft function. After microencapsulation in barium alginate beads the islets were cultured for another day. Diabetic LEWIS rats (blood glucose >19 mM) were transplanted with 3500 immunoaltered mc-Wistar islets intraperitoneally. Controls were transplanted with 3500 non-cultured syngeneic or allogeneic mc-islets. Additional syngeneic and allogeneic controls were transplanted with 6000 non-cultured, non-encapsulated islets intraperitoneally. Seventy percent of the recipients of microencapsulated, long-term low temperature cultured islets maintained normoglycemia at least for 15 weeks, while this was true in only 17% of those animals receiving microencapsulated non-pretreated allogeneic islets. Islets in non-encapsulated controls were rejected within several days. Graft function correlated with histologically proven viable islets within the capsules. Microencapsulation of islets markedly prolonged allograft survival compared to non-encapsulated islets; application of an immunoaltering low-temperature culture further improved graft function significantly. These data may support the hypothesis of induction of a reaction against microcapsules by the antigen release from the graft which may be avoided by immunoaltering islet pretreatment.     

原子力显微镜对APA生物薄膜超微结构的研究

本文采用原子力显微镜（ＡＦＭ）对ＡＰＡ生物薄膜的超微结构进行了观测研究。选择出最佳观察方法。结果发现薄膜上分布有不规则的微孔,其长短孔径之比大约为３∶２,微孔的中心距为孔径的２倍     

水温变化对藻酸盐印模材料精度及凝固时间的影响

目的 探究水温变化对藻酸盐印模材料流动性、工作时间、凝固时间和形变量的影响。方法分别将液剂控制在4种不同水温（8℃、14℃、23℃和32℃）下用全自动印模调拌机调拌藻酸盐粉体,通过比较4组藻酸盐印模材料在玻璃板上的流动性,观测测量工作时间、凝固时间;利用模具套件制取印模,再观察印模形变量。采用SPSS 24.0软件包对数据进行统计学分析,比较各组之间的差异。结果 4种不同温度液剂调制的藻酸盐印模材料的流动性从大到小依次为8℃组>14℃组>23℃组>32℃组,且不同组别间差异具有统计学意义（P<0.05）。工作时间及凝固时间从短到长依次为32℃组<23℃组<14℃组<8℃组,各组间差异具有统计学意义（P<0.05）,32℃组的工作时间（29.3±1.0）s和凝固时间（41.0±1.4）s以及8℃组的凝固时间（133.2±3.8）s均不符合临床使用要求。各组形变量之间存在差异,但不具有统计学意义（P>0.05）。结论在一定范围内,水温变化和藻酸盐印模材料的流动性、工作时间及凝固时间呈负相关,临床使用时以14℃～25℃的水温较合适。     

生长激素-海藻酸钠-壳聚糖微胶囊的制备及药物释放性能研究

目的 研究生长激素-海藻酸钠-壳聚糖微胶囊的制备及其释放性能. 方法 本课题采用脉冲电场法制备生长激素-海藻酸钠-壳聚糖微球.根据单因素试验和正交试验结果,优化工艺条件和处方组成.观测其形态、尺寸,鉴别其组分,测定生长激素含量、包封率和回收率,并进行体内、外释放实验. 结果 选择450μm锐孔直径、2cm液面距、1.5%海藻酸钠浓度、8ml/h推进速度、2%Ca2+浓度作为最佳工艺条件.光学显微镜观察可见得到的微胶囊具有很好的圆形形态,平均粒径尺寸为47.93μm.微胶囊的平均包封率为94%,他莫昔芬平均含量为11.24%.体外模拟胃液中,微球不溶胀而且所载生长激素基本不被释放;在模拟肠液中,微球溶胀而且所载生长激素被缓释出来,并且在12h后被完全释放出来.体内实验证实生长激素微球组的血药浓度在8h时到达峰值(98.59ng/ml).体内、外释放证实能够达到延缓释放的目的. 结论 生长激素-海藻酸钠-壳聚糖微球具有良好的圆形形态和较好缓释效果.     

碱性成纤维细胞生长因子缓释系统促进颌面部骨折愈合的实验研究

目的：探讨碱性成纤维细胞生长因子（basic fibroblast growth factor,bFGF）缓释系统加速兔下颌骨骨折愈合的作用和机理。方法：采用32只成年新西兰兔制备下颌骨线形骨折模型,实验组骨折处分别覆盖bFGF/胶原复合膜和bFGF/藻酸钙凝胶,对照组仅涂布50μg bFGF,空白对照组未加任何生长因子和缓释系统。术后2、4、8、12周行组织学和免疫组化检查。结果：bFGF缓释系统实验组骨折处新骨形成明显快于对照组,bFGF在骨折愈合8周后仍有高强度表达,骨折区有大量血管生成;空白对照组2周时bFGF有较弱的表达,4周后bFGF的表达不明显。bFGF/胶原复合膜组和bFGF/藻酸钙凝胶组实验组间成骨速度、血管形成量和bFGF的表达情况无显著差异,胶原的降解速度快于藻酸钙凝胶。结论：bFGF缓释系统能在骨折愈合期间持续释放bFGF生长因子,并加快下颌骨骨折的愈合速度,缩短骨折临床愈合时间,具有理想的临床应用前景。