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Biomedical subjects

C A Finch

Publications and source records attributed to C A Finch.

At least 145 records · Page 8Linked to original sources
PubMed1974

Storage iron kinetics. VII. A biologic model for reticuloendothelial iron transport.

The processing of erythrocyte iron by the reticuloendothelial cell has been characterized by kinetic measurements of blood radioactivity made after the intravenous injection of heat-damaged erythrocytes labeled with (59)Fe and of transferrin-bound (55)Fe. The early reticuloendothelial release of iron, a matter of hours, was calculated from the plasma turnover rate of (55)Fe and the plasma reappearance of (59)Fe. Late release was calculated from the ratio of the cumulative incorporation of both tracers into the circulating red cell mass over a period of 2 wk. There was an initial processing period within the reticuloendothelial cell, after which radioiron either rapidly returned to circulation (t(1/2) 34 min) or was transferred to a slowly exchanging pool of storage iron within the reticuloendothelial cell (t(1/2) release to plasma of 7 days). These pathways were of equal magnitude in the normal dog. Reticuloendothelial release of iron was largely independent of the pre-existing plasma iron level or transferrin saturation. Diurnal fluctuations in the plasma iron level were shown to be the result of a variable partitioning of iron between the early and late release phases. Acute inflammation resulted in a prompt and marked increase in the fraction of iron stored (late phase), whereas depletion of iron stores resulted in a marked increase in early release.

Animals↗
PubMed1972

Food iron absorption measured by an extrinsic tag.

The paper describes the use of an extrinsic tag of inorganic radioiron to determine the total absorption of nonheme iron from a complete meal. The method was developed by measuring the iron absorbed from vegetable foods containing biosynthetically incorporated (55)Fe (intrinsic tag) and from (59)Fe added as a small dose of inorganic iron to the same meal (extrinsic tag). In studies with maize, black bean, and wheat, a consistent extrinsic: intrinsic radioiron absorption ratio averaging 1.10 was observed. Similar results were obtained with either ferrous or ferric iron as the extrinsic tag, and with doses of the latter ranging from 0.001 to 0.5 mg iron added to a test meal containing 2-4 mg of food iron. Adding the radioiron at different stages in preparation of the test meal also had little effect. Separate administration of the extrinsic tag was less satisfactory when small portions of a single food were employed, but with a complete meal, the separate dose was preferable. The extrinsic tag provided a valid measure of absorption despite marked differences in the iron status of the subject, and with wide changes in absorption imposed by adding desferrioxamine or ascorbic acid to the test meal. These findings indicate that there is a common pool of nonheme iron, the absorption of which is influenced by various blocking or enhancing substances present in the meal.

Adult↗