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Biomedical subjects

A Katayama

Publications and source records attributed to A Katayama.

124 records · Page 7Linked to original sources
PubMedDate not supplied

Characterization of peroxidases in luminol chemiluminescence coupled with copper-catalysed oxidation of cysteamine.

Hydrogen peroxide formed during the course of the copper(II)-catalysed oxidation of cysteamine with oxygen was continuously determined by a peroxidase (POD)-catalysed luminol chemiluminescence (CL) method. Horseradish peroxidase (HRP), lactoperoxidase (LPO) and Arthromyces ramosus peroxidase (ARP) were used as a CL catalyst. The respective PODs gave specific CL intensity-time profiles. HRP caused a CL delay, and ARP gave a time-response curve which followed the production rate of H2O2. LPO gave only a weak CL flash which decayed promptly. These differences of CL response curves could be explained in terms of the different reactivities of PODs for superoxide anion and the different formation rate of luminol radicals in the peroxidation of luminol catalysed by POD.

Copper↗
PubMedDate not supplied

Non-polypoid colorectal neoplasias: a multicentric study.

A total of 781 non-polypoid colorectal neoplasias harvested at 4 main Hospitals in Tokyo, Japan (n = 420) and at 4 different time-intervals at the Karolinska Hospital, Stockholm, Sweden (n = 361) were reviewed. By applying strict histologic definitions, the lesions were classified into adenomas with low grade dysplasia (LGD), with high grade dysplasia (HGD), intramucosal carcinomas (IMC) or submucosal carcinomas (SMC). Of the non-polypoid neoplastic lesions reviewed in Sweden, 82.8% (n = 299) had LGD. In Japanese patients only 42.6% (n = 179) had LGD (p < or = 0.001). On the other hand, as many as 42.4% (n = 178) of the non-polypoid lesions in Japanese patients had HGD, but only 14.1% (n = 51) of those in Swedish patients (p < or = 0.001). Whereas 15.0% (n = 63) of the non-polypoid neoplasias seen in Japan were IMC or SMC, only 3.0% (n = 11) of those seen in Sweden were IMC or SMC (p < or = 0.001). The cause(s) for these differences remains unclear. In Japan, however, a marked increased incidence of colonic cancer has been recorded in later years. Whether the "catching up phenomenon" by the Japanese with western colonic cancer incidence includes increased histologic aggressiveness of non-polypoid neoplastic polyps--as found in this survey--remains to be elucidated.

Adenoma↗
PubMedDate not supplied

Ethnic or environmental differences in disparate geographic regions may influence the histology of flat colorectal neoplasias.

Histologic sections of endoscopically flat colorectal polyps removed in Tokyo and Stockholm were reviewed. A total of 178 flat colorectal neoplasias (88 from the Tokyo Medical College Hospital, Tokyo and 90 from the Karolinska Hospital, Stockholm) were classified following strict histologic criteria by two different pathologists (one Swedish and the other Japanese). The number of polyps with high grade dysplasia, with intramucosal carcinoma and with invasive carcinoma were significantly higher (p < 0.001) in Tokyo (61.4% or 54/88) than in Stockholm (15.0% or 14/90). The present results suggest that flat colorectal neoplasic polyps may be histologically more "severe" and more "aggressive" in Japanese than in Swedish patients. The possibility that more "advanced" lesions had been inadvertently removed in Tokyo was discounted as Japanese endoscopists were also instrumental in excising many of the flat colorectal polyps in Stockholm. Ethnic and/or environmental differences seem to play a crucial role in the evolution of flat colorectal neoplasic polyps from LGD and HGD, to intramucosal and to invasive carcinoma.

Adult↗