PubMed Health⌕ Search

Biomedical subjects

Y Kusano

Publications and source records attributed to Y Kusano.

43 records · Page 3Linked to original sources
PubMed1986

Biochemical evidence for existence of immunoreactive renin in human prolactinoma tissue.

High activity of renin was demonstrated in human prolactinoma tissue. This activity was almost completely inhibited by specific antibody raised against human renal renin, indicating that it was not due to the nonspecific action of proteases. The specific activity of renin was 5.04 ng of angiotensin I generated/mg of protein per h, comparable to that of the pituitary tissue prepared from postmortem human subjects. The biochemical properties of the prolactinoma renin were generally similar to those of well-known kidney enzyme, such as molecular mass (Mr = 46,000), optimum pH (6.0), and glycoprotein nature. However, the isoelectric points (pI) of the prolactinoma renin (pI = 4.90, 5.04, 5.24 and 5.41) differed somewhat from those of plasma and kidney renins reported hitherto. These results indicate that true renin can be produced in human prolactinoma tissue.

Chromatography, Affinity↗
PubMed1986

[The effect of metoclopramide and dopamine on mineralocorticoid secretion--in vivo and in vitro studies].

There is considerable information suggesting that dopamine is a physiological regulator of aldosterone secretion. Metoclopramide, a specific dopamine antagonist, elicits a rapid rise in plasma aldosterone independent of the known aldosterone-regulating factors. However, the mechanism and the site of action of metoclopramide, whether adrenal or extra-adrenal, in stimulation of aldosterone production remain to be defined. The present studies were designed to investigate the mechanism of dopaminergic control of corticosteroid secretion and to determine at which step in the aldosterone biosynthetic pathway metoclopramide and dopamine exert their effect. Plasma concentrations of progesterone, 11-deoxycorticosterone (DOC), and cortisol were not altered by a bolus intravenous administration of 10 mg metoclopramide in 8 healthy male volunteers. Metoclopramide increased plasma aldosterone from 6.9 +/- 2.8 (Mean +/- 2SD) ng/100 ml to a maximum level of 18.2 +/- 4.7 ng/100 ml, 18-hydroxycorticosterone (18-OHB) from 12.6 +/- 6.5 ng/100 ml to a maximum of 41.3 +/- 7.3 ng/100 ml and corticosterone from 0.36 +/- 0.09 microgram/100 ml to a maximum of 0.85 +/- 0.22 microgram/100 ml. The aldosterone, 18-OHB and corticosterone responses displayed a parallel time course, with a significant response of each occurring within 5 minutes after metoclopramide administration. These data suggest that metoclopramide may modulate the activities of 18-hydroxylase and 11 beta-hydroxylase. Studies in vitro revealed that metoclopramide (10(-8)-10(-4) M had little effect on basal production of aldosterone, 18-OHB and corticosterone from human adrenal slices. Dopamine (10(-4) M) did not alter the basal secretion of aldosterone, 18-OHB and corticosterone, but suppressed the secretion of these 3 mineralocorticoids by ACTH, which were diminished by addition of 10(-4) M metoclopramide. There was a concentration-dependent inhibitory effect of dopamine on conversion of corticosterone to 18-OHB and DOC to corticosterone in vitro using bovine adrenal mitochondrial fractions. IC50 of dopamine inhibiting 18-hydroxylation and 11 beta-hydroxylation were 7.5 X 10(-7) M and 9.5 X 10(-4) M, respectively. It appears that physiological concentration of dopamine can modulate the activity of 18-hydroxylase enzyme. In summary, it can be concluded that the in vivo and in vitro studies are compatible with a view that dopamine has a physiological role in the regulation of aldosterone by modulating the activity of 18-hydroxylase enzyme.

18-Hydroxycorticosterone↗
PubMed1985

[The effects of o,p'-DDD on adrenal steroidogenesis and hepatic steroid metabolism].

O,p'-DDD is used for the treatment of adrenocortical carcinoma and Cushing's disease. The inhibitory effect of this drug on the adrenal steroid biosynthesis has been described by many authors, but there are very few reports about the sites of action of this drug on adrenal steroid synthesis. This paper presents in vitro studies on adrenal steroidogenesis and hepatic steroid metabolism. The effects of o,p'-DDD on adrenal 3 beta-hydroxysteroid dehydrogenase (3 beta-HSD), 11 beta-hydroxylase (11 beta-OHlase) and 18-hydroxylase (18-OHlase) were examined in vitro using mitochondrial and microsomal fractions prepared by standard centrifugation procedures from the homogenate of bovine adrenal cortices. The concentrations of o,p'-DDD inducing 50% inhibition of 3 beta-HSD, 11 beta-OHlase and 18-OHlase were 8 X 10(-6) M, 1 X 10(-5) M and 3 X 10(-6) M, respectively. This study clearly demonstrates the marked inhibitory effects of o,p'-DDD on 3 beta-HSD in vitro, which was not described previously. The inhibitory effects of o,p'-DDD on these 3 enzymes were diminished by an addition of 0.05 approximately 0.5 mM of cofactor (NADPH or NAD). The results indicate that o,p'-DDD may reduce NADPH or NAD utilization, resulting in the inhibition of steroidogenesis. The effects of o,p'-DDD on hepatic 5 beta-reductase were examined in vitro using rat liver homogenate. O,p'-DDD inhibits 5 beta-reductase, resulting in the decrease of conversion of cortisol to dihydrocortisol and tetrahydrocortisol at the concentration of 10(-3) M.

18-Hydroxycorticosterone↗
PubMed1981

Amino acids derivatives synthesis from nitrogen, carbon and water by electric discharges.

Electric discharges between a pair of carbon electrodes were continued for 50 days in a vessel of 5 liters in volume which initially contained nitrogen at a pressure of 15 cm Hg and 200 ml of water. The pressure in the vessel was gradually increased to 60 cm Hg at the end of the run. Gas chromatographic analysis showed that the increase of the pressure mainly results from the production of hydrogen and carbon monoxide. The concentration of ammonia in the aqueous sample was increased to 0.05 M in 50 days of the discharge. After hydrolysis, glycine and serine were detected at the concentrations of 3.4 x 10(-3) M and 0.057 x 10(-3) M in the final solution, respectively, though glycine was found only at the concentration of 6 x 10(-6) M before hydrolysis. TLC analysis indicated the presence of hydantoic acid, N-formylglycine, diketopiperazine, and polymers of glycine.

Amino Acids↗