The Effectiveness of Self-Expandable Metallic Stent Insertion in Treating Right-Sided Colonic Obstruction: A Comparison between SEMS and Decompression Tube Placement and an Investigation of the Safety and Difficulties of SEMS Insertion in Right Colons.

Objectives. Self-expandable metallic stent (SEMS) is widely used to treat malignant colonic obstruction. However, most reports about SEMS insertion have concentrated on the left colon. This study aimed to (1) investigate the effectiveness of SEMS insertion compared with conventional decompression tube for right-sided colonic obstruction and (2) compare the safety and technical success of SEMS insertion between left- and right-sided colonic obstructions. Methods. The data from thirty-seven patients who underwent SEMS or conventional decompression tube placement for malignant colonic obstruction in our hospital were analyzed retrospectively. Technical and clinical success, complications, and technical difficulties were analyzed. We compared the results between SEMS insertion and decompression tube placement in right colons and the outcomes of SEMS insertion between right- and left-sided colonic obstructions. Results. For right colons, the clinical success rate of SEMS insertion (100%) was significantly higher than that of decompression tube placement (55.9%). Concerning SEMS insertion, the technical difficulty and safety of SEMS insertion were similar between right- and left-sided colonic obstructions. Conclusion. SEMS insertion for right-sided colon is significantly more effective than conventional decompression tube placement, and this procedure was safer and less technically challenging than expected. SEMS insertion should be considered for treating right-sided malignant colonic obstruction.

DNA fragmentation and detachment of enterocytes induced by anti-CD3 mAb-activated intraepithelial lymphocytes.

To elucidate the role of intraepithelial lymphocytes (IEL) and enterocytes in the defense mechanism of the small intestine, we designed experiments to stimulate the IEL by anti-CD3epsilon, anti-TCRalphabeta, or anti-TCRgammadelta monoclonal antibodies (mAbs), and to examine the subsequent changes to the enterocytes. The enterocytes of the duodenum and jejunum, but not of the ileum, showed massive DNA fragmentation 30 min after intraperitoneal injection of anti-CD3 mAb. These responses were also induced by anti-TCRgammadelta mAb, but not by anti-TCRalphabeta mAb, and were completely inhibited by cyclosporin A. Nearly half of the enterocytes of the villi in the duodenum and jejunum were exfoliated into the lumen 4 h after the injection of the mAb. Administration of anti-CD3 mAb also induced DNA fragmentation in Fas-deficient MRL/lpr mice, indicating that the Fas-Fas ligand system was not involved in these events. The anti-CD3 mAb treatment also induced massive DNA fragmentation in the intestinal epithelium of the duodenum and jejunum in TNF-receptor-1-deficient mice, whereas TNF-alpha induced only the detachment of intestinal epithelium of wild-type mice, implying the dissociation of two independent factors and/or mechanisms for DNA fragmentation and the subsequent epithelial cell detachment in the murine duodenum and jejunum. The mAb failed to exfoliate the epithelium in TNF-R1-deficient mice. Thus, TCRgammadelta(+) IEL, when treated with anti-CD3 or anti-TCRgammadelta mAbs, induced rapid DNA fragmentation and subsequent detachment of the duodenal and jejunal epithelia, but not in the ileum ("the silent ileum"), partly because of the paucity of TCRgammadelta(+) IELs in the ileum.

Distribution of two types of lymphocytes (intraepithelial and lamina-propria-associated) in the murine small intestine.

The intestine, which is exposed to nutrition and to food-derived antigens and microbes including viruses and bacteria, might be an important site for the immune response. Crucial structural and functional differences exist between the small and large intestine, regional differences even having been demonstrated within the small intestine. Accordingly, intraepithelial lymphocytes (IELs) and lamina propria lymphocytes (LPLs) might be heterogeneous among the different intestinal regions. The aim of this study has been to describe, as accurately as possible, the numbers and T-cell receptor (TCR) phenotypes of IELs and LPLs present in distinct regions of the murine small intestine under physiological conditions. Using an immunohistological technique to differentiate IELs from LPLs, the differential enumeration of IELs and LPLs in distinct regions of the murine small intestine, based upon their definition originally determined by their location, has been performed for the first time and has demonstrated that (1) there are more IELs than LPLs in the duodenum and jejunum, but more LPLs than IELs in the ileum, (2) in the duodenum and jejunum, TCRgammadelta IELs account for 70%-75% of the total CD3(+) IELs, a much greater percentage than previously reported, (3) the ratio of TCRgammadelta to TCRalphabeta IELs is inverted in the ileum, with more than 75% IELs being TCRalphabeta-positive, (4) the lamina propria forms one functional unit throughout the small intestine in terms of the TCR subset components (TCRalphabeta:TCRgammadelta=3:1), and (5) the ileum is entirely different from other regions of the small intestine. To deepen our understanding of the functional significance of the small intestine as an immunologically competent organ, the precise distributions of IELs and LPLs, the ratio of their various subsets, and the strict distinction of IELs and LPLs, as described in this study, is indispensable.