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首页> 外文学位 >Mechanisms of Staphylococcus epidermidis RP62A adhesion to biomedical polymers: The role of platelets, plasma proteins and polymer surface characteristics as studied under dynamic flow.
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Mechanisms of Staphylococcus epidermidis RP62A adhesion to biomedical polymers: The role of platelets, plasma proteins and polymer surface characteristics as studied under dynamic flow.

机译：表皮葡萄球菌RP62A粘附于生物医学聚合物的机理：在动态流动下研究的血小板，血浆蛋白和聚合物表面特征的作用。

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摘要

The effects of plasma proteins, biomaterial surface characteristics, and platelets on Staphylococcus epidermidis strain RP62A adhesion to biomedical polymers were studied using the rotating disk system. The rotating disk system generated well-defined shear conditions, simulating the hemodynamics of normal human circulation. Bacterial adhesion was quantified by the adhesive coefficient, defined as the percentage of bacteria transported to the surface that becomes adherent. Polymers studied include National Heart, Lung, and Blood Institute (NHLBI) reference polyethylene and polydimethylsiloxane, Silastic{dollar}spcircler,{dollar} expanded polytetrafluoroethylene, Dacron{dollar}spcircler,{dollar} and argon plasma treated polyethylene.; In comparing adhesion studies conducted in phosphate buffered saline (PBS) and 1% solution of plasma proteins in PBS, staphylococcal adhesion to all of the polymers studied were reduced by the presence of adsorbed plasma proteins. This reduction was statistically significant across the entire range of shear stress studied. Surface modification of polyethylene by argon plasma treatment also reduced bacterial adhesion relative to the untreated polymer. In the presence of adsorbed plasma proteins, argon plasma treated polyethylene had the lowest adhesive coefficients of all of the materials tested. The result is consistent with thermodynamic analysis of the bacterial adhesion process, i.e., increasing polymer surface tension would reduce staphylococcal adhesion.; The highest adhesive coefficients were recorded for woven Dacron graft material. The surface topography of this biomaterial created turbulence under flow, resulting increased bacterial flux to the surface. Furthermore, significant number of bacteria were "adherent" via physical entrapment in the interstices of the fibers. For cases such as this, physical forces dominate and even overwhelm the thermodynamics of the adhesion process. In the same light, increasing shear stress reduces the number of adherent bacteria. However, even with argon plasma treatment polyethylene and adsorbed plasma proteins, the highest normal physiologic shear stress cannot detach all of the adherent bacteria.; In studying Staphylococcus epidermidis adhesion to polyethylene with heparin anticoagulated platelet-rich plasma, it was observed that surface-activated platelets, occupying only 4% of the disk surface, mediated the adhesion of 50% of the adherent bacteria. Repeating this study using sodium citrate as the anticoagulant, Staphylococcus epidermidis did not exhibit preferential adhesion to contact-activated platelets on the polymer surface. This suggests a calcium-mediated staphylococcal adhesion to platelets. The reduction of bacterial adhesion by adsorbed plasma proteins was unaffected by the choice of anticoagulant.; Thus our studies demonstrate that (1) increasing polymer surface tension by biologic or artificial surface modification effect a lower bacterial adhesion; (2) hemodynamic shear conditions in conjunction with surface topography may create physical forces that dominate the adhesion process; and (3) platelets are potent mediators of staphylococcal adhesion to biomaterial surface and this mechanism may be a calcium-dependent process.
机译：使用旋转磁盘系统研究了血浆蛋白，生物材料表面特征和血小板对表皮葡萄球菌RP62A菌株对生物医学聚合物粘附的影响。旋转盘系统产生了明确定义的剪切条件，模拟了正常人循环的血液动力学。细菌的粘附力通过粘附系数来量化，粘附系数定义为被转移到粘附表面的细菌百分比。研究的聚合物包括美国国家心脏，血液和血液研究所（NHLBI）参考聚乙烯和聚二甲基硅氧烷，Silastic {dollar} spcircler，{dollar}膨胀聚四氟乙烯，Dacron {dollar} spcircler，{dollar}和经氩气等离子体处理的聚乙烯。在比较在磷酸盐缓冲盐水（PBS）和1％血浆蛋白在PBS中的溶液中进行的黏附研究时，葡萄球菌对所有研究聚合物的黏附因吸附血浆蛋白的存在而降低。在所研究的整个剪应力范围内，这种降低具有统计学意义。相对于未处理的聚合物，通过氩等离子体处理的聚乙烯表面改性也降低了细菌粘附。在吸附的血浆蛋白存在下，经氩气等离子体处理的聚乙烯在所有测试材料中的粘合系数最低。该结果与细菌粘附过程的热力学分析一致，即，增加聚合物表面张力将减少葡萄球菌粘附。织造的涤纶接枝材料记录了最高的粘合系数。这种生物材料的表面形貌在流动下产生湍流，导致细菌向表面的通量增加。此外，大量细菌通过物理夹带“粘附”在纤维的空隙中。对于这种情况，物理力占主导地位，甚至压倒了粘合过程的热力学。同样，增加剪切应力会减少附着细菌的数量。然而，即使用氩等离子体处理的聚乙烯和吸附的血浆蛋白，最高的正常生理切应力也不能使所有粘附细菌分离。在研究肝素抗凝富含血小板的血浆对表皮葡萄球菌对聚乙烯的粘附时，观察到表面活化的血小板仅占磁盘表面的4％，介导了50％粘附细菌的粘附。重复使用柠檬酸钠作为抗凝剂的这项研究，表皮葡萄球菌对聚合物表面的接触活化血小板没有表现出优先的粘附性。这表明钙介导的葡萄球菌对血小板的粘附。抗凝剂的选择不影响吸附的血浆蛋白对细菌粘附的减少。因此，我们的研究表明：（1）通过生物或人工表面改性提高聚合物表面张力会降低细菌附着力； （2）结合表面形貌的血液动力剪切条件可能会产生主导粘附过程的物理力； （3）血小板是葡萄球菌粘附至生物材料表面的有效介体，这种机制可能是钙依赖性过程。

著录项

  • 作者

    Wang, I-Wen.;

  • 作者单位

    Case Western Reserve University.;

  • 授予单位 Case Western Reserve University.;
  • 学科 Engineering Biomedical.; Health Sciences Medicine and Surgery.
  • 学位 Ph.D.
  • 年度 1996
  • 页码 184 p.
  • 总页数 184
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类 生物医学工程;
  • 关键词

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