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Biomedical subjects

A Katayama

Publications and source records attributed to A Katayama.

At least 91 records · Page 5Linked to original sources
PubMed1992

[Morphological comparison between pm-carcinoma and minute ss-carcinoma of the gallbladder].

Eleven cases of pm-carcinoma and thirty cases of minute ss-carcinoma of the gallbladder were compared with their morphologies and biological behavior with reference to the assessment of pm-carcinoma as early carcinoma. The vascular permeation and lymph nodal metastasis was 9% and 0%, respectively, in the pm-carcinoma and 43% and 9% in the minute ss-carcinoma. The 5-year survival rate of the pm-carcinoma was better (100%) than the minute ss-carcinoma (73.3%). The poorly differentiated adenocarcinoma or well differentiated adenocarcinoma with high grade atypia in the invasive-area was higher in incidence in the minute ss-carcinoma. From these findings it is concluded that the pm-carcinoma should be defined as early carcinoma in the gallbladder. The both carcinomas were hardly distinguishable macroscopically. Therefore, the careful examination of resected gallbladder by stepwise sections is important.

Adenocarcinoma↗
PubMed1991

Hair cell regeneration: the identities of progenitor cells, potential triggers and instructive cues.

Hair cells are produced and accumulate in the ears of fish and amphibians as they grow during postembryonic life; hair cell regeneration occurs in lateral line organs in those groups and in the cochlea in birds. Continuous time-lapse microscopy has directly demonstrated that supporting cells divide to give rise to hair cells during regeneration in lateral line neuromasts. Supporting cells also appear to give rise to hair cells during regeneration in the avian ear, but additional cell types have been proposed as hair cell progenitors. Alternative interpretations of current evidence are discussed in relation to the possibility that supporting cells may be the common progenitor in all cases of hair cell regeneration. The regenerative proliferation of hair cells in birds occurs in populations of cells that are mitotically quiescent in undamaged ears. Evidence suggests that the extrusion of damaged hair cells and the breaking of intercellular junctional adhesions may be a trigger for regenerative proliferation. The potential triggering influence of phagocytes is also discussed. The differentiation of replacement cells during regeneration in the cochlea may be regulated by surface interactions between cells. A model that could account for the reconstitution of the mosaic pattern of hair cells and supporting cells is proposed.

Animals↗
PubMed1989

Cell production in the chicken cochlea.

In the chicken cochlea, the structural features of the cilia bundles of individual hair cells vary systematically along the length of the sensory epithelium. As a first approach to understanding the developmental mechanisms that underlie this precise arrangement of structurally distinct hair cells, the spatiotemporal pattern of the terminal mitoses of their precursor cells was investigated by administering 3H-thymidine, a radioactive precursor to DNA. This demonstrated that the first hair cells were produced during the sixth day of incubation and formed a longitudinal band that extended along most of the length of the sensory epithelium. The epithelium grew further through appositional addition of hair cells at the edges of this first band of cells, and the hair cell addition process expanded into the surrounding areas during the next 3 days. By the ninth day of incubation all the hair cells in the sensory epithelium except for those at the peripheral edges in the distal (apex) portion had been produced through terminal mitoses. Our results have demonstrated that hair cells that have similar stereocilia phenotypes do not all leave the mitotic cycle at the same time.

Animals↗
PubMed1989

WS-9659 A and B, novel testosterone 5 alpha-reductase inhibitors isolated from a Streptomyces. II. Structural elucidation of WS-9659 A and B.

On the basis of spectroscopic and chemical evidence, the structures of WS-9659 A and B isolated as inhibitors of testosterone 5 alpha-reductase from a Streptomyces have been established as 1 and 2, respectively. The reductase inhibitory activities of the derivatives 5 and 6, and degradation products 3 and 8 were considerably less active and substantially inactive, respectively.

5-alpha Reductase Inhibitors↗
PubMed1985

Postnatal development of auditory function in the chicken revealed by auditory brain-stem responses (ABRs).

Auditory evoked brain-stem responses (ABRs) were recorded from the surfaces of the brain of lightly anesthetized newborn (1-7 days old) and adult (7-9 weeks old) chickens as a measure of the development of auditory processing. One-day-old and older chickens showed a series of waves within 5 msec after the stimulus onset. This precocity of the ABR in chickens contrasts with the first appearance of the ABR in cats at 4 days of age. The ABR onset latency was shorter in adult chickens than in newborns. This indicates that developmental modifications of mechanical transmission in the external and middle ear or cytodifferentiation of the sensory hair cells of the basillar papilla and the neurons of the acoustic nerve continue postnatally. Within the complex wave form of the response, most of the inter-wave latencies decreased with maturation, indicating that development of the central auditory pathway also continues postnatally. One inter-wave latency (N1 to P3-4) was significantly shorter (P less than 0.05) in adults than in newborns for intense click stimuli, and even among newborns, this inter-wave latency was significantly shorter in 6- and 7-day-old specimens than in 1-3-day-old specimens. It seems likely that changes in the N1 to P3-4 inter-wave latency reflect changes in evoked activity of second order auditory neurons that are located in the nucleus angularis and nucleus magnocellularis, and that intensive developmental changes occur in these neurons during the first postnatal week. The ABR recorded in chickens is a reliable measure of functional activity in the auditory system which is reproducible between individuals and capable of demonstrating developmental changes in specific segments of the wave form.

Animals↗