The interactions between retinoic acid-(RA)-dependent transcriptional regulatory sequences of the 5-untranslated region of the thrombomodulin gene and nuclear RA-responsive proteins were studied using human pancreas BxPC-3 cells. Deletion mutants of pTM-CAT plasmid revealed the presence of distal and proximal RA-responsive regions containing direct repeat with 4 spaces (DR4) and three of four Sp1 sites, respectively. Cotransfection of a pTM-CAT plasmid with expression plasmids of RA receptors (RAR␣, RAR␤, and RAR␥) augmented the promoter activity under the condition of lower retinoid X receptor-␣ (RXR␣) expression, whereas the activity was greatly diminished when RXR␣ was highly expressed. An electrophoretic mobility shift assay with cDNA containing the DR4 indicated that heterodimers of RAR and RXR␣ interacted with the DR4 site, although the interaction gradually disappeared with the increase in the ratio of RXR␣/RAR. On the other hand, Sp1 protein interacted especially with the tandem Sp1 site corresponding to the first and second Sp1 sequences of the four Sp1 sites in the proximal RA-responsive region. The binding of Sp1 to Sp1 sites was independent of RAR-RXR heterodimer but increased with the increase in Sp1 concentration in the presence of unknown factor(s) of reticulocyte lysate. Upon treatment of the cells with RA, time-dependent increases in the ratio of RAR␤ to RXR␣ and the phosphorylated form of Sp1 were observed. We concluded that two genomic DNA regions, the DR4 site (؊1531 to ؊1516) and the first and second Sp1-binding sites (؊145 to ؊121), were involved in the RA-dependent augmentation of thrombomodulin gene expression through increased interactions of the two regions with heterodimer of RAR-RXR␣ and nuclear Sp1, respectively. Thrombomodulin (TM)1 is an essential cofactor for activation of protein C by thrombin on vascular endothelial cells (1-3). TM expression of human endothelial cells is decreased by tumor necrosis factor-␣ (4 -6), interleukin-1 (6, 7), endotoxin (8), and phorbol ester (5, 6) and oxidized LDL (9, 10), but we have found that it is increased by all-trans-retinoic acid (t-RA) (11, 12) and/or cAMP (11, 13) in human umbilical vein endothelial (HUVE) cells, through the acceleration of transcriptional activity. Several studies on the regulatory region of human TM gene have been reported (14 -17), and Dittman et al. (17) showed the existence of an RA response element (RARE) in the 5Ј-flanking region of the gene. The direct effects of retinol and its derivatives (retinoids), such as t-RA and 9-cis-RA (9C-RA), on the expressions of many genes are apparently mediated by nuclear receptor proteins that are members of the steroid and thyroid hormone receptor (TR) superfamily of transcriptional regulators (18, 19). Nuclear retinoid receptor dimers, of which retinoid X receptor (RXR) is a mandatory constituent, are required for effective activation of the t-RA and/or 9C-RA response pathways (20 -25). However, the direct repeats of RARE separated by 4 base sequences (DR4) at Ϫ1531 to Ϫ1516 fro...

The palisade vessels present at the distal end of the esophagus are considered to be a landmark of the esophagogastric junction and indispensable for diagnosis of columnar-lined esophagus on the basis of the Japanese criteria. Here we clarified the features of normal palisade vessels at the esophagogastric junction using magnifying endoscopy. We prospectively studied palisade vessels in 15 patients undergoing upper gastrointestinal endoscopy using a GIF-H260Z instrument (Olympus Medical Systems Co., Tokyo, Japan). All views of the palisade vessels were obtained at the maximum magnification power in the narrow band imaging mode. We divided the area in which palisade vessels were present into three sections: the area from the squamocolumnar junction (SCJ) to about 1 cm orad within the esophagus (Section 1); the area between sections 1 and 3 (Section 2); and the area from the upper limit of the palisade vessels to about 1 cm distal within the esophagus (Section 3). In each section, we analyzed the vessel density, caliber of the palisade vessels, and their branching pattern. The vessel density in Sections 1, 2, and 3 was 9.1 ± 2.1, 8.0 ± 2.6, and 3.3 ± 1.3 per high-power field (mean ± standard deviation [SD]), respectively, and the differences were significant between Sections 1 and 2 (P= 0.0086) and between Sections 2 and 3 (P < 0.0001). The palisade vessel caliber in Sections 1, 2, and 3 was 127.6 ± 52.4 µm, 149.6 ± 58.6 µm, and 199.5 ± 75.1 µm (mean ± SD), respectively, and the differences between Sections 1 and 2, and between Sections 2 and 3, were significant (P < 0.0001). With regard to branching form, the frequency of branching was highest in Section 1, and the 'normal Y' shape was observed more frequently than in Sections 2 and 3. Toward the oral side, the frequency of branching diminished, and the frequency of the 'upside down Y' shape increased. The differences in branching form were significant among the three sections (P < 0.0001). These results indicate that the density of palisade vessels is highest near the SCJ, and that towards their upper limit they gradually become more confluent and show an increase of thickness. Within a limited area near the SCJ, observations of branching form suggest that palisade vessels merge abruptly on the distal side. We have demonstrated that palisade vessels are a useful marker for endoscopic recognition of the lower esophagus.

The nucleotide sequence coding for 726 amino acid residues of the alpha-chain of rabbit C3 was determined from a cDNA clone. Subfragments of the cDNA produced by restriction endonucleases were inserted into the bacteriophage M13 and sequenced using the dideoxynucleotide technique. The derived amino acid sequence was compared with those of human and mouse C3, which have been previously reported [by De Brujn, M.H.L. and Fey, G.H. (1985) Proc. Natl. Acad. sci. USA 82, 708, and Westel, R.A. et al. (1984) J. Biol. chem. 259, 13857, respectively]. There was 79% or 78% homology in amino acid sequence between rabbit and human or mouse C3, respectively. All of the cysteinyl residues were conserved among the three molecules, and the sequence around the thioester site was also highly conserved. Several regions having low homology were found: one of them was the small fragment released by factor I cleavage.

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