Takao Tashiro

Histamine H2 Receptor Antagonism by T-593: Studies on cAMP Generation in Hepa Cells Expressing Histamine H2 Receptor

Histamine H2 receptor antagonism by T-593 was investigated in Hepa cells expressing canine histamine H2 receptors. T-593 inhibited generation of cAMP in Hepa cells stimulated by 10–5 mol/l histamine with an IC50 value of 2.3 × 10–6 mol/l, (S)-(–)-T-593, one of the enantiomers comprising racemic T-593, inhibited cAMP generation with an IC50 value of 6.1 × 10–7 mol/l. On the other hand, the other enantiomer (R)-(+)-T-593 exhibited only a negligible effect. Incubation of the cell with (S)-(–)-T-593 for 60 min depressed the maximal response of the concentration-response curve of histamine with a nonparallel rightward shift. The slope of a Schild plot was 1.27. In contrast, (S)-(–)-T-593 caused a parallel rightward shift of the curve, with a Schild plot slope that did not significantly differ from unity, by treating the cells for 15 min. The H2 receptor-blocking action of (S)-(–)-T-593 remained almost unaffected after washing out the drug, whereas the effect of ranitidine was reversible after washing. These results suggest that T-593 possesses a time-dependent unsurmountable antagonistic action against histamine H2 receptor. T-593 may interact with the histamine H2 receptor molecule in a slowly associable and dissociable manner.

A Case of Extensive Gastrointestinal Involvement of Malignant Lymphoma Associated with Early Gastric Carcinoma

Abstract: Described is a 59 year old Japanese man With malignant lymphoma involving the stomach, duodenum, terminal ileum, colon and rectum, who developed early gastric carcinoma. Repeated gastroduodenoscopy revealed various appearances of the gastrointestinal involvement in malignant lymphoma, such as giant folds, polypoid lesions, and ulcerations, in addition to a depressed lesion of early gastric carcinoma. Colonoscopy also showed multiple polypoid lesions throughout the large bowel. Though the gastrointestinal involvement in malignant lymphoma is not rare, diffuse multiple polypoid lesions in the entire large bowel as seen in our case have rarely been endoscopically described.

Ascending Colon Stenosis:A Rare Presentation of Perforated Appendicitis

Abstract: Described is a 49‐year‐old Japanese male who developed an ascending colon stenosis secondary to perforated appendicitis. The patient was examined at our hospital because of an abdominal pain and the presence of a firm mass in the right flank. A barium enema and colonoscopic examination revealed an ascending colon stenosis with multiple nodular elevations. On laparotomy, an inflammatory mass, originating from a ruptured appendix, was found adhered to the cecum and the ascending colon. Thus, a right hemicolectomy was performed. Microscopic examination revealed a periappendiceal abscess with marked submucosal fibrosis and lymphoid hyperplasia of the ascending colon and cecum.