Iodine-129 as a protein label for studies of plasma protein turnover and its measurement with neutron activation analysis

\u3cp\u3eIodine-129 (t\u3csub\u3e 1 2\u3c/sub\u3e = 1.57 × 10\u3csup\u3e7\u3c/sup\u3ey) was used as a protein label for the measurement of the turnover rate of albumin in two human subjects. Plasma samples were assayed for \u3csup\u3e129\u3c/sup\u3eI using destructive neutron activation analysis. The experiment entailed an estimated radiation dose of 0.2 μSv to the total body of the subjects. The turnover parameters showed reasonable agreement with literature values. When in a rabbit the catabolism of (\u3csup\u3e129\u3c/sup\u3eI + \u3csup\u3e131\u3c/sup\u3eI)-labeled autologous albumin was followed, the results obtained with both labels agreed well.\u3c/p\u3

In vitro exchangeable erythrocytic zinc

\u3cp\u3eExchangeable erythrocytic zinc is measured by\u3csup\u3e65\u3c/sup\u3eZn uptake in and release from erythrocytes under standarized and near, physiological conditions: 7.6 μM zinc and 580 μM albumin in the medium. The intracellular exchangeable erythrocytic zinc pool in healthy volunteers amounts to 5 μmol zinc/L packed cells. The half-time of the exchange is 7 h, its activation energy 84 kJ/mol. The effects of the variation in temperature and the concentrations of albumin, as well as the effects of some zinc carriers, cell transport inhibitors, and stress hormones on the\u3csup\u3e65\u3c/sup\u3eZn uptake are measured.\u3c/p\u3