CT findings in runner's colitis.

A spectrum of lower gastrointestinal tract symptoms occurs in marathon runners. Although most symptoms are transient, reversible ischemic colitis is a rare complication that typically responds to supportive therapy. Because computed tomographic features have not been previously described to our knowledge, we describe abdominal computed tomographic manifestations of reversible ischemic colitis in three marathon runners. On computed tomography, reversible ischemic colitis involves the cecum, with varying involvement of the proximal colon.

Effects of heat shock, stannous chloride, and gallium nitrate on the rat inflammatory response.

Heat and a variety of other stressors cause mammalian cells and tissues to acquire cytoprotection. This transient state of altered cellular physiology is nonproliferative and antiapoptotic. In this study, male Wistar rats were stress conditioned with either stannous chloride or gallium nitrate, which have immunosuppressive effects in vivo and in vitro, or heat shock, the most intensively studied inducer of cytoprotection. The early stages of inflammation in response to topical suffusion of mesentery tissue with formyl-methionyl-leucyl-phenylalanine (FMLP) were monitored using intravital microscopy. Microvascular hemodynamics (venular diameter, red blood cell velocity [Vrbc], white blood cell [WBC] flux, and leukocyte-endothelial adhesion [LEA]) were used as indicators of inflammation, and tissue levels of inducible Hsp70, determined using immunoblot assays, provided a marker of cytoprotection. None of the experimental treatments blocked decreases in WBC flux during FMLP suffusion, an indicator of increased low-affinity interactions between leukocytes and vascular endothelium known as rolling adhesion. During FMLP suffusion LEA, an indicator of firm attachment between leukocytes and vascular endothelial cells increased in placebo and gallium nitrate-treated animals but not in heat- and stannous chloride-treated animals, an anti-inflammatory effect. Hsp70 was not detected in aortic tissue from placebo and gallium nitrate-treated animals, indicating that Hsp70-dependent cytoprotection was not present. In contrast, Hsp70 was detected in aortic tissues from heat- and stannous chloride-treated animals, indicating that these tissues were in a cytoprotected state that was also an anti-inflammatory state.

The fate of antibodies bound to the surface of tumor cells in vitro.

The fate of monoclonal antibodies binding to the surface of human tumor cells in vitro was investigated. Seven antibodies, labeled with 125I, were tested on four cell lines, which included a melanoma and carcinomas of the ovary, kidney, and lung. The antibodies were selected only by the criterion that they not be rapidly internalized via coated pits, so that they would be representative of most antibodies reacting with cell surface antigens. After allowing binding during a 2-h incubation, unbound antibody was removed, and the release of intact or degraded antibody in the supernatant was monitored. The data demonstrate that most bound antibody was gradually degraded and released from the cell over a 2-3-day period, probably via internalization, while only a small fraction, less than 20% for most antibodies, appeared to dissociate intact. One exceptional antibody, MW207, dissociated largely intact. The release of intact antibody was virtually complete within 4 h, and radioactivity released after this time was predominantly in degraded form. These results demonstrate that antibody binding to the surface of viable cells must in general be considered irreversible, and hence the concept of affinity is not applicable. Since an Fab fragment of one of the antibodies dissociated rapidly, such irreversible binding appears to require bivalent attachment. Another conclusion of this study is that most antibodies binding to the cell surface are gradually internalized, which we suggest is due to the normal turnover of cell surface constituents via non-clathrin-dependent endocytosis. Several experimental approaches indicated that a large fraction of antibody retained by the cells, for at least 2 days after binding, was present at the cell surface.