Miguel Layrisse

Iron Fortification of Flours in Venezuela

This paper reviews a conference about the impact of the iron fortification program in Venezuela; it was presented at the Pan American Health Organization regional technical meeting: “Iron Fortification: Where Are We in Terms of Iron Compounds,” held in Washington January 10–12, 2001. Some of the data presented were published in the American Journal of Clinical Nutrition , including stimulating results about the impact of fortification of precooked corn and white wheat flours, as well as the prevalence of anemia and iron deficiency in the Venezuelan population. This article reports results from three surveys carried out in 1997, 1998, and 1999 on the same age and socioeconomic group that had been evaluated in 1990, 1992, and 1994. This article also shows the impact of iron fortification programs and the influence of other factors on the prevalence of iron deficiency and anemia during the last 7 years.

Thin-layer chromatographic detection of metal-EDTA complexes in human faeces

The application of a thin-layer chromatographic technique combined with ion-exchange chromatography for the detection of metal-EDTA complexes in human faeces is described. Reproducible separations were obtained on silica gel and cellulose pre-coated plates using appropriate solvent systems. These complexes were easily identified from the specific colours produced after spraying with an appropriate reagent. Using this procedure, it was possible to detect some of these complexes when added to human faeces in amounts corresponding to approximately those which would be formed if a meal (containing the normal requirements for the metals) were fortified with the recommended maximum amount of Fe(III)-EDTA (10 mg of Fe as the complex). However, when the experiment was carried out in vivo, that is, the subjects ingested a meal together with the complex, or with Fe(III)-EDTA plus ten times the normal requirements of the metals as inorganic salts, none of the complexes was detected in the faeces in either instance.

A Sensitive Micromethod for the Study of Iron Uptake by Mitogen-Stimulated Human Blood Mononuclear Leukocytes

Abstract To study the uptake and utilization of Fe by human mononuclear leukocytes (MNL), we have evaluated a micromethod which makes use of the culture in microtiter plates. MNL were isolated from human blood by Ficoll-Hypaque sedimentation, cultured under standard conditions at 10 5 MNL/well and stimulated with PHA (5μg/ml) for 72 hr. The cells were pulsed with 59 Fe-Transferrin (TF) or 3 H-TdR for the last 24 hr., then harvested, processed and counted using standard procedures. The results show that 59 Fe-TF is taken up by proliferating MNL, the maximal uptake paralelling the incorporation of 3 H-TdR. We applied the method to cultures set up at different cell densities and observed a close relationship between the number of cells in culture and the iron uptake. The method is sensitive and highly reproducible. Moreover, the cultures can be harvested and processed more rapidly and easily than in other methods reported previously.

Lymphocyte Activation, Iron Uptake and Release by Human Mononuclear Leukocytes in Tiie Presence of Desferrioxamine

Desferrioxamine (DFO), an iron chelating drug, has been shown to inhibit the proliferative response of leukocytes to mitogen. In the present study we investigated the effect of DFO on different aspects of human mononuclear leukocyte (MNL) function in vitro. DFO, added at the beginning of the culture period, inhibited both tritiated thymidine and radioiron uptake by phytohemagglutinin-stimulated MNL and the degree of inhibition correlated with the degree of cellular activation, to the extent that in the absence of mitogen a significant stimulatory effect of DFO was observed, especially when iron supplement was present in the culture medium. However DFO was not found to inhibit iron uptake directly, and relatively low concentrations of iron as iron-transferrin totally reversed the inhibitory action of DFO on thymidine uptake. Although the release of iron from preloaded MNL in the presence of DFO was only 15% greater than the spontaneous release of control cultures, we conclude that the site of action of DFO is an intracellular iron pool, that increases in importance when the supply of iron to the cellular iron metabolism become limiting as in optimally activated MNL.