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G Vanderhoff

Publications and source records attributed to G Vanderhoff.

5 recordsLinked to original sources

Iron removal from transferrin. An experimental study.

We have studied the facilitation of iron transfer from transferrin to desferrioxamine by various anions. Most of the anions which can substitute for HCO-3 in the ternary complex of transferrin - Fe - HCO3 do not facilitate iron transfer; anions which do facilitate iron transfer do not necessarily form stable ternary complexes. Combinations of anions effective in transfer have a less-than-additive effect, suggesting a common reaction pathway. We suggest that the transfer of iron from transferrin to desferrioxamine involves a substitution step and a subsequent chelation step, and that the efficiency of the overall reaction is a function of both these attributes of the anion.

Deferoxamine↗

Chelate mediated transfer of iron from transferrin to desferrioxamine.

Desferrioxamine, widely used for the treatment of iron overload in Cooley's anaemia, binds iron so tightly that it should quantitatively remove iron from transferrin. Studies conducted in vivo and in vitro, however, have failed to demonstrate significant depletion of transferrin-bound iron by a stoichiometric excess of desferrioxamine. However, low molecular weight chelating agents, capable of forming ternary complexes with transferrin and ferric iron, can promote a rapid transfer of iron from transferrin to desferrioxamine. A possible mechanism for this facilitated exchange is offered.

Chelating Agents↗

Metabolic effects of antisickling amounts of nitrogen and nor-nitrogen mustard on rabbit and human erythrocytes.

Nitrogen mustard (NH2) and Nor-nitrogen mustard (Nor-HN2) both inhibit the polymerization of deoxyhemoglobin S in solution and in intact erythrocytes. Metabolic studies were undertaken to determine the feasability of an extracorporeal treatment with these or related agents. Glucose utilization, hexose monophosphate shunt activity, methemoglobin reduction, and incubation with acetylphenylhydrazine for Heinz body formation were performed, as well as specific assays for hexokinase, pyruvate kinase, glucose-6-phosphate dehydrogenase, glutathione reductase, ATP, reduced glutathione (GSH), and survival of autologous mustard-treated cells in rabbits. HN2 was found to enter red cells rapidly and bind to intracellular contents. Metabolic studies revealed no significant inhibition or alteration of function by Nor-HN2 at 10 mg/ml of whole blood. Rabbit red cell survival was also normal. HN2, however, inhibited glutathione reductase and blocked the free sulfhydryl group of GSH by forming serveral addition products of alkylated GSH. Heinz body test with acetylphenylhydrazine became positive in HN2-treated cells, and rabbit red cell survival was shortened considerably in the concentration range used to inhibit sickling. Ascorbic acid stimulation of the hexose shunt pathway was inhibited by HN2, but methylene blue stimulation remained unaffected. 14-C-HN2 remains bound to red cells in vivo, and the disappearance of radioactivity is similar to that found with 14-C-DFP (disopropylfluorophosphate). Oxygen affinity of both HN2 and Nor-HN2 treated human red cells remains virtually the same as that found in control samples. It is concluded that Nor-HN2 may be a suitable agent for an extracorporeal therapy, and that each mustard needs to be evaluated individually for its antisickling effects and its suitability for extracorporeal use.

Animals↗