Mechanism of edge restenosis after sirolimus-eluting stent implantation.

OBJECTIVES: The present study evaluated the mechanism of edge restenosis after sirolimus-eluting stent (SES) implantation using serial (post-intervention and follow-up) intravascular ultrasound (IVUS) analysis. BACKGROUND: There is little information about the mechanism of edge restenosis after SES implantation. METHODS: Serial IVUS analysis was performed at 5 mm reference segments immediately proximal and distal to the SES in 25 lesions with edge restenosis. Proximal and distal reference segments were divided into 1 mm subsegments. RESULTS: Between post-intervention and follow-up IVUS studies, a decrease in external elastic membrane area was observed at the proximal edge. There was a significant increase in plaque & media area in the subsegment closest to the proximal edge. On the other hand, there was an increase in plaque & media area at the distal edge, with no change in external elastic membrane area. CONCLUSIONS: There may be different mechanisms between proximal and distal edge restenosis after SES implantation. Negative remodeling plays a major role in proximal edge restenosis. On the other hand, intimal hyperplasia may mainly contribute to distal edge restenosis.

A histochemical and immunohistochemical investigation of guanase and nedasin in rat and human tissues.

Human guanase is known as a specific enzyme in the liver, kidney, and brain. However, its functional significance remains poorly understood. In addition, interestingly, a different organ distribution between humans and rats was suggested. Here, we performed immunohistochemical staining with anti-human nedasin (neuronal and endocrine discs large/SAP102 associated protein), whose sequence was identical to that of guanase, antibody and histochemical staining for guanase in normal tissues of rat and human liver, kidney, and small intestine, and compared the results. Guanase activity was observed uniformly in the rat hepatocytes, biliary epithelium and vascular endothelium cells, while it was localized to the hepatocytes and biliary epithelium in the human liver. When the histochemical staining for guanase and the immunohistochemical staining for nedasin were compared, the stained regions were different in the rat liver but were almost consistent in all human tissues. Totally consistent staining results were also obtained between rats and humans in the other organization except the liver. Based upon the research reports to date, the experiments on guanase and nedasin in rat organs performed in this study are considered to have important implications in the investigation of their physiological significance.

Clinical value of the determination of serum guanase activity in patients with chronic hepatitis type C.

The study examines the clinical significance of guanase (GU) measurement in patients with hepatitis C. 688 patients in whom either ALT was abnormal, or in whom HBsAg or HCVAb was detected in the serum, were enrolled into this study. The percentage of cases in which normal ALT while elevated GU was compared among the different disease groups. Then, the percentage of cases with normal ALT but elevated GU was compared between HBV and HCV groups. For the entire population, a significant correlation was observed between ALT and GU (r=0.872). The overall percentage of cases with normal ALT but elevated GU activity was 11.4%. In HCV group, 449 cases had normal ALT. Of these cases, 20.3% had elevated GU, while ALT was normal. Before 1989, no test to check donated blood for HCV antibody was available. However, screening of donated blood for high GU was associated with a reduced incidence of post-transfusion hepatitis. This is probably because following the screening, blood donated by patients with hepatitis C who had normal ALT but elevated GU was rejected. After the introduction of HCV antibody measurement, GU measurement is still useful to reveal the pathophysiological condition in-patients with chronic hepatitis type C.