RICKETTSIA RICKETTSII IN HUMAN ENDOTHELIAL CELLS

落基山斑疹热 (RMSF) 由立克次体引起，是 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 小血管细胞。 此次调查的主要目的是 确定细胞损伤人体血管的具体机制 立克次体引起的内皮细胞，并检查潜在的 血小板粘附于感染内皮细胞的生物学后果 细胞。 了解立克次氏菌损伤细胞的机制 血小板粘附于通常非血栓形成的物质的后果 表面应该有助于更好地理解 RMSF的发病机制，并可以提供更具体的治疗 严重形式疾病的管理。 这项研究将专门在人类内皮细胞中进行 利用生化和电子相结合从脐静脉中提取 显微技术。 内皮细胞损伤引起的假说 立克次氏体是细胞内立克次体的直接结果 新陈代谢，将受到考验。 具体来说，脂质过氧化 有毒自由基破坏细胞内膜，导致细胞膜扩张， 内质网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同时进行 作为两种 ER 膜标记物葡萄糖-6-磷酸酶和 细胞色素 P-450 因过氧化而被破坏。 类固醇 并且将检查抗氧化剂谷胱甘肽和维生素E的作用 作为自由基清除剂的保护能力。 超氧化物的影响 将歧化酶掺入单层脂质体中并添加到 R 中。 将研究立克次体感染的内皮细胞以确定是否 生物体引起的细胞损伤可以被改变。 血小板研究 使用[3H]腺嘌呤和扫描电子显微镜观察粘附性，以及 使用 [3H] 血清素的粘附血小板的激活状态也将 研究过。 最后，作为未来研究的前奏，将进行尝试 分离并鉴定立氏立克次氏菌的质粒 DNA。

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.