RICKETTSIA RICKETTSII IN HUMAN ENDOTHELIAL CELLS

落基山斑疹热（RMSF），由立克次氏体引起， 被认为是最严重的人类立克次体病。 假定目标 感染细胞是内皮细胞，偶尔是平滑肌细胞 小血管的细胞。 这次调查的主要目的是 以确定细胞损伤的具体机制， 引起内皮细胞坏死。立克次氏体，并检查潜在的 血小板粘附于受感染内皮细胞的生物学分支 细胞 对R.立克次体和 血小板粘附于正常非血栓形成的 表面应大大有助于更好地理解 的发病机制，并可提供更具体的治疗 管理严重的疾病形式。 本研究将专门在人内皮细胞中进行 来自脐静脉，使用组合的生化和电子 显微技术。 假设内皮细胞损伤导致 由R.立克次体是细胞内立克次体 代谢，将被测试。 具体来说， 有毒自由基引起的细胞内膜扩张， ER的解体并最终导致细胞裂解。 分析 丙二醛的水平，过氧化的主要降解产物， 超氧阴离子和超氧化物歧化酶也将进行 作为两种ER膜标记物，葡萄糖-6-磷酸酶和 细胞色素P-450，由于过氧化作用而被破坏。 类固醇 抗氧化剂谷胱甘肽和维生素E将被检查， 作为自由基清除剂的保护能力。 超氧化物的影响 歧化酶掺入单层脂质体中并加入到R. 将研究立克次体感染的内皮细胞，以确定是否 可以改变生物体引起的细胞损伤。 血小板研究 粘附使用[3 H]腺嘌呤和扫描电子显微镜，和 使用[3 H] 5-羟色胺的粘附血小板的活化状态也将是 研究了 最后，作为未来研究的前奏， 分离并鉴定了R.立克次氏体

Rocky Mountain spotted fever (RMSF), caused by Rickettsia rickettsii, is considered the most severe of the human rickettsioses. The putative target cells of infection are the endothelial cell and occasionally smooth muscle cells of small blood vessels. The primary purpose of this investigation is to determine the specific mechanism of cell injury to human vascular endothelial cells cause by R. rickettsii, and to examine the potential biological ramifications of platelet adherence to infected endothelial cells. Understanding of the mechanism of cell injury by R. rickettsii and the consequences of platelet adherence to a normally non-thrombogenic surface should contribute considerably to a better undertanding of the pathogenesis of RMSF, and could provide for more specific therapeutic management of severe forms of the disease. This study will be carried out exclusively in human endothelial cells derived from the umbilical vein using combined biochemical and electron microscopic techniques. The hypothesis that endothelial cell injury caused by R. rickettsii is the direct result of intracellular rickettsial metabolism, will be tested. Specifically, that lipid peroxidation of intracellular membranes by toxic free radicals leads to dilatation and disorganization of the ER and eventually to lysis of the cell. Analysis of levels of malonaldehyde, the primary degradation product of peroxidation, and superoxide anion and superoxide dismutase will be carried out as well as the activity of two ER membrane markers, glucose-6-phosphatase and cytochrome P-450 which are destroyed as a result of peroxidation. Steroids and the antitoxidants glutathione and vitamin E will be examined for their protective capacity as free radical scavengers. The effects of superoxide dismutase incorporated into unilamellar liposomes and added to R. rickettsii-infected endothelial cells will be studied to determine whether cell injury caused by the organisms can be modified. Studies on platelet adherence using [3H] adenine and scanning electron microscopy, and the activation status of adherent platelets using [3H] serotonin will also be studied. Lastly, as a prelude to a future study, an attempt will be made to isolate and characterize plasmid DNA from R. rickettsii.