Carbon nanotubes are highly versatile materials; new applications using them are continuously being developed. Special attention is being dedicated to the possible use of multiwall carbon nanotubes in biomaterials contacting with bone. This study describes the response of murine macrophage-like Raw 264.7 cells after two and six days of culture in contact with artificially generated particles from both, ultra-high molecular weight polyethylene polymer and the composite (multiwall carbon nanotubes and ultra-high molecular weight polyethylene). This novel composite has superior wear behavior, having thus the potential to reduce the number of revision knee arthroplasty surgeries required by wear failure of tibial articulating component and diminish particle-induced osteolysis. The results of an in vitro study of viability, and interleukin-6 and tumor necrosis factor-alpha production suggest good cytocompatibility, similar to that of conventional ultra-high molecular weight polyethylene.

Previous studies have shown that stress can induce inflammatory responses in the body, and contribute to deficits in learning and memory. Whether or not this is a causal relationship, however, is not well understood. This study investigated immune and inflammatory changes induced by stress; we hypothesized that cytokine secretion and white blood cell (WBC) profiles would be altered by stress exposure. Adult male rats were restrained for 30 min, and brain tissue and blood harvested 2h after the end of the stress. Flow cytometry was used to count T‐ and B‐cells from the WBC fraction of the blood. Blocks of brain tissue containing hippocampal and hypothalamic regions were dissected, homogenized in PBS, and a Milliplex MAP kit used to measure multiple cytokines in these samples and in the plasma. Acute stress did not significantly alter cytokine levels in any of our tissues. A significant reduction was seen, however, in the number of B‐cells in acutely stressed rats compared to controls (p<0.05). In conclusion, our data support our hypothesis in part, as changes in immune or inflammatory factors were seen after acute stress. Future studies will confirm and extend these data, determine the role of B‐cells during stress, and examine these responses in repeatedly stressed animals.Supported by: 8G12MD007592