ABSTRACT
delta-Aminolevulinic acid (delta-ALA) synthetase in mouse liver homogenate was significantly (p less than 0.001) higher in the presence of uremic compared with normal plasma, the ratio of the two values being 1.36 +/- 0.24 in 30 paired experiments. This effect does not seem to be due to increased concentrations of urea or creatinine nor to any possible dialyzable substances. Its relationship to the retention of an inducing factor or decreased production of erythropoietin in uremic patients is discussed. A possible inhibitory effect of erythropoietin on liver delta-ALA synthetase is suggested.
Subject(s)
5-Aminolevulinate Synthetase/metabolism , Liver/enzymology , Uremia/blood , Adolescent , Adult , Aged , Animals , Erythropoietin/blood , Female , Heme/biosynthesis , Humans , In Vitro Techniques , Male , Mice , Middle AgedABSTRACT
A mathematical model with nonlinear time-varying characteristics has been developed which describes the relationship between the kinetics of natural aging and radiation-induced delayed mortality. Based on this model, it appears that there is an immediate effect of radiation which is continuously, but nonlinearly, increasing in severity. Two phases appear in this variation, corresponding to the two phases (plateau and dying phase) of the mortality curves for control populations. Accordingly, S/E (survival time post-irradiation/further expectation of life) can best be interpreted as an increasing function during the plateau phase of normal mortality curves, which levels off during the ensuing dying phase.
