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Biomedical subjects

S Kuwano

Publications and source records attributed to S Kuwano.

At least 19 recordsLinked to original sources
PubMed1994

Impression of smoothness of a sound stream in relation to legato in musical performance.

Physically continuous sounds do not always produce the subjective impression of legato. In the present study, the effect of temporal factors on the impression of smoothness of a sound stream was systematically investigated in relation to the dynamic characteristics of hearing. The results showed that decaying sounds, successively presented, were perceived as being marginally connected when the sounds physically overlapped, while steady-state sounds were perceived as being marginally connected when they were physically separated. It was also shown that judgments by the subjects agreed quite well with the effect intended by the pianist when the passage was given in different temporal interpretations.

Adolescent↗
PubMed1993

Suppression of the purgative action of rhein anthrone, the active metabolite of sennosides A and B, by calcium channel blockers, calmodulin antagonists and indomethacin.

The involvement of Ca2+ in the mechanism of the purgative action of rhein anthrone was studied. Among individual or combination pretreatments with calcium channel blockers, calmodulin antagonists and prostaglandin biosynthesis inhibitors, the combination of indomethacin and nifedipine completely blocked the diarrhoea induced by rhein anthrone and also inhibited its effects on colonic fluid and electrolyte transport, and large intestinal motility. Calmodulin antagonists were less active regarding suppression of the effects of rhein anthrone. We concluded that, in addition to prostaglandins, diarrhoea induced by rhein anthrone must also involve the calcium channel which can be blocked by nifedipine, but not verapamil.

Animals↗
PubMed1992

Metabolic activation of sennoside C in mice: synergistic action of anthrones.

Sennosides A and C directly injected into the caecum of mice showed equal purgative activity. Intracaecal administration reduced time to onset of diarrhoea induced by sennoside C from about 3 h after oral administration to about 24 min. At 2.3 h after oral administration of sennoside C, nearly equimolar amounts of aloe-emodin anthrone and rhein anthrone were detected in the large intestine of mice. The purgative effect of oral sennoside C could be reduced by pretreating mice with chloramphenicol. This was observed as a decreased formation of total anthrones in the large intestine. Both anthrones and an equimolar mixture of both anthrones directly injected into the caecum exerted a purgative effect, although the activity was lower for aloe-emodin anthrone. The intracaecal ED50 values were 54.5 (24.1-89.6), 11.4 (5.0-15.7) and 11.2 (6.1-14.6) mumol kg-1 for aloe-emodin anthrone, rhein anthrone and an equimolar mixture of both anthrones, respectively. We concluded that aloe-emodin anthrone and rhein anthrone, formed mainly by intraluminal bacterial action, are the true active metabolites of sennoside C in mice and that both anthrones synergistically exert their purgative effects on mice.

Animals↗
PubMed1991

Suppression of the purgative action of rhein anthrone, the active metabolite of sennosides A and B, by indomethacin in rats.

Rhein anthrone (12.48 mg kg-1) produces watery and mucoid diarrhoea approximately 20 min after intracaecal administration to rats. Pretreatment with the prostaglandin (PG) biosynthesis inhibitor indomethacin (10 mg kg-1, i.p.) only delayed and did not completely block the onset of the induced diarrhoea. Rhein anthrone stimulated PGE2 release into the rat colonic lumen and the increased release was depressed by indomethacin. Rhein anthrone also accelerated large intestinal transit and this acceleration could be partly inhibited by indomethacin, which was probably responsible for the delay in the onset of diarrhoea. Indomethacin prevented the enhanced water, K+ and mucus secretion and the reduced Na+ absorption in the colon which were induced by rhein anthrone. The net water secretion could not be reversed to net absorption and the mucus secretion was only slightly depressed by indomethacin. Thus, our findings suggest that other mechanisms, together with the PG-dependent mechanism, are involved in the purgative action of rhein anthrone in rats.

Animals↗
PubMed1990

Prostaglandin E2-mediated stimulation of mucus synthesis and secretion by rhein anthrone, the active metabolite of sennosides A and B, in the mouse colon.

Rhein anthrone, the active metabolite of sennosides A and B, stimulated PGE2 release into the mouse colonic lumen. At 6.24 mg kg-1, it decreased net water and Na+ absorption significantly in the case of water, but could not reverse the net absorption in mouse ligated colon, although it enhanced net K+ secretion. Pretreatment with indomethacin diminished the effects of rhein anthrone except on K+ net secretion. Rhein anthrone or PGE2 markedly stimulated mucus secretion and synthesis in mouse ligated colon. The enhanced mucus secretion and synthesis induced by rhein anthrone were significantly suppressed by pretreatment with indomethacin. Our results have shown that the colonic secretion of water and electrolytes mediated by PGE2 is partly involved in the rhein anthrone-induced diarrhoea but that in mice, the mucoid diarrhoea induced by rhein anthrone results mainly from PGE2-mediated mucus synthesis and secretion in the colon.

Animals↗
PubMed1988

Involvement of prostaglandin E-like material in the purgative action of rhein anthrone, the intraluminal active metabolite of sennosides A and B in mice.

Intracaecal administration of rhein anthrone, the intraluminally active metabolite of sennosides A and B, to mice quickly induced severe diarrhoea. Pretreatment with the prostaglandin (PG) biosynthesis inhibitor, indomethacin, and PGE2 antagonist, SC-19220, prevented the onset of diarrhoea induced by rhein anthrone, but the PGE2 antagonist polyphoretin phosphate (PPP) showed only a weak inhibitory effect. Rhein anthrone stimulated the production of PGE-like material only in the colon and its large intestinal propulsive activity was depressed by indomethacin and SC-19220, but not by PPP which suggests that the release of PGE-like material has some role in its purgative action.

Animals↗
PubMed1985

Isolation of a new aloe-emodin dianthrone diglucoside from senna and its potentiating effect on the purgative activity of sennoside A in mice.

Two aloe-emodin dianthrone diglucosides (I and II) were isolated from the leaves of Cassia angustifolia Vahl by successive column chromatography with Amberlite XAD-2, silica gel, Polyamide C-200 and Sephadex LH-20. The stereostructures of I and II were elucidated as trans and meso isomers at 10-10', respectively, from the patterns of the ultraviolet absorption spectra and circular dichroism curves. This is the first report of isolation of diglucoside I from senna. Despite the lack of purgative activity, diglucoside I exerts a potentiating effect of about 1.3 times on the purgative activity of sennoside A in mice when even 15% is included in the mixture. The difference between I and a third active glycoside based on aloe-emodin is also discussed.

Aloe↗