[Advances in thermodynamic analysis of heat capacity function].
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Biomedical subjects
Publications and source records attributed to S Kidokoro.
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Alkylehter and ester derivatives of the antitumor cyclic hexapeptide RA-V obtained from the roots of Rubia cordifolia (Rubiaceae) were synthesized and bioassayed for activity against cultured tumor cells. RA-V and its n-hexylether showed significant effects against human nasopharynx carcinoma (KB), P388 lymphocytic leukemia and MM2 mammary carcinoma cells. The activity values (log 1/IC50) of ether derivatives of RA-V gave an upward parabolic or bilinear relationship when plotted against log P (P: partition coefficient determined with the 1-octanol/water system) as the carbon number of the side chain at the phenol moiety of RA-V was increased, the optimum log P values being in the range from 3.5 to 4.9. The ester derivatives showed a similar relationship, the optimum log P values being 6.3-6.7, which is higher than that of the ether derivatives. The lethal effect of RA-V on KB cells was clearly different from that of mitomycin C, and RA-V was concluded to be a "time-dependent drug" like vinblastine.
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In order to study the control system of plasma aldosterone in human, we examined the effects of low salt plus upright posture, angiotensin II, ACTH and potassium upon plasma renin activity, aldosterone and cortisol in five subjects who were supposed to be normal. All of the procedures, low salt diet with below 3 g of salt and 2 hr-upright posture, 0.25 mg of Cortrosyn, angiotensin infusion to increase 20mmHG of diastolic pressure for an hour, and 30 mEq of potassium infusion stimulated plasma aldosterone significantly. Furthermore, in each subject the degrees of response to each of these stimulations were almost same. In an old woman aged 68, responses to all of stimulations were significantly lower than those in other subjects. Plasma cortisol was significantly stimulated by ACTH, but slightly reduced by potassium infusion. From these results, it is certain that plasma aldosteron levels are easily affected by a small amount of changes in angiotensin, ACTH, potassium and sodium. However, responses of aldosterone to these changes seem to be decreased in old subjects.
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